Well the K3's look thin on the ground on this forum so I'll start asking questions.
The one I have just bought has hard and soft tops, currently the hard top is fitted but there is so much water inside the car that the sound deadening has gone all mushy and mouldy big time and I've ripped it out. I think that the water is coming in via the joint of the roof meeting the screen top. The previous owner/s have made do with a very thin strip of rubber as the seal and when you use the two levers to secure the roof at the front there is no effort required and one of the levers just swings down on it's own so is doing nothing.
I haven't tried fitting the soft top as yet so don't know if this is a better fit or not.
My first reaction is to replace the "seal" with some thicker rubber section or tube and see if that helps and then when the weather is warmer perhaps make a tongue and groove arrangement where the two meet.
Anyone been there done that.

I have been told that a good soft top leaks less than the hard top, so that is one bit of good news for you.

I'd buy a cover to help when the rain is bad, if the car is to be kept outside.

The seal is best if made continuous from the hinge on one door to the hinge on the other. If the seal stops at either side of the roof, then it will form a point to drip from, which will be onto either your leg, or the seat!

Having a strip around the window, to stop the rain getting the wrong side of the window should help too.

As long as the strip is thick enough to seal, then I don't think it needs to be any thicker.

I discovered to my cost some if the water I was getting in was coming down the screen then down front of the 'tub' then in where the heater (n/s) and pedal box (o/s) were not well sealed.

The other annoyance has been mentioned already - the join where the hard top lits off - it's nicely placed to drip on your leg.(or wet the seat if parked)

In rain the other pest is that my wiper parks to the left so (on intermittent wipe) all the water moved down the screen then slowly comes up again once the wiper has parked

I'll check the heater and pedal box area and re seal if necessary. If the wiper parking is an issue have you thought of rainX treatment? I've used it on a couple of fast cars as it helps when going for it in the wet. Most of the 24hour cars at Le Mans use it as the wipers can't cope with the amount of water at the speeds they are doing and you can still use your wipers without wiping the rainX off, only needs reapplying every few weeks or months depending on the amount of rain driven in. Maybe worth a try.

I can vouch for the fact that on my K3 the soft top sealed much better on the top of the windscreen than the hardtop. My temporary fix for the hardtop was to tape over the gap! However, water gathered on top of the sills and on very wet days would come in where the gear linkage/handbrake cables passed through the tub.

Rainex - I use also theres a washer bottle rainex to help keep the 'coating' intact, I use that also.

I've never seen water come in the gear linkage holes ! Another anoyance is on a warm day as you drive with the windows down you get a blast of hot air thru that hole, to stop it you need to shut the windows.

Well I managed to get a few days to work on the car over the festive period and as a temporary "fix" I sandwiched a piece of rubber tubing between the top of the screen and the hard top, this has resulted in no further water penitration from that area so will now source some "D" shaped rubber seal that I can stick to the vertical face of the front of the hard top and that should do that job.
I have also looked at other areas with regards water ingress and have started to place a rubber seal under all the bolts that go through the body into the main tub just in case and I will possibly fabricate a better seal for where the hoses enter the tub and then go into the sills. (looks too easy for water to bridge the deflectors that are there at the moment).
As I had to ditch the sound deadening I have also fitted rubber washers to the bolts that secure the seats and the centre console as it was easier to remove them to get the mouldy rubbish out and dry the inside off a bit.

Sounds like you've been getting on well over the holiday, sounds good.

Progress not too bad but as I'm working on it outside rather than in the garage (too many projects etc.) the weather has a say.
This last weekend I found more water inside and located it to the rear sides of the hard top so have started to glass in some extra bits so that I can seal it all up nicely (can't see why this area was not done in a similar fashion from the begining as it is an obvious place for the water to go), anyway hopefully with a bit more time I should have it sorted for when the new underlay and seals turn up later this week. Weather permiting.

Hi all, having now got the K3 out of garage ready for MOT the weekend before last, just in time for some of the heaviest rain we had this year. Well it seems I thought that rubber seals would prevent water ingress but I was wrong. I now have wet driver’s seat and about 6 inches of water in the foot wells . Spent most of this weekend trying to dry it all out.
I have now put “duck tape” on the side of the hard top where it meets the tub, behind the doors, looks naff , but does seem to stop the water leaking in at that point. At the front is the real problem is, water runs along the hard top to windscreen seal and back through the gap in door/roof seal and into the K3. It was like a tap during the rain shower on Saturday. Not sure yet the best way to stop this, as the only way seems to be permanently fixing the hardtop on and put a rain gutter along the roof.
I can see why the soft top has a better water seal at the top of the screen, because it over laps the top of the screen surround, where as the hard top doesn’t. This has the advantage of not leaving the join as channel to each door. Although I not sure it still won’t do the same when driving, as water will be forced under the soft top’s front lip and then it got go either into the car directly or sideways in thorough the door seal gap like the hard top.

I was thinking of actually adding fibreglass to the windscreen edge and roof around the door to extend the profile further out than the edge of the door glass so that when the rain does find its way off the roof it drips on the door skin and not the interior obviously i need to make sure it still looks pretty and not a botch when i eventually get round to it i,ll post some pictures.

Well you be glad to know I seem to have a water tight K3 , I put the hard top on using a black silicon bath sealer, I have also added some “guttering” up screen pliers and above the doors all sealed with same silicon. The guttering stops the water running off the roof and lying on the door rubbers and running in through the roof join and screen at top of the A post. I will take some pictures and post them up if I can. They are made from ally and have not been painted.
Looks like I may have remove the roof and refit it as the silicon sealant does not seem to have hardened properly, black streaks down the side of the car and I get black on my figures if I touch the sealant. Last time I buy stuff from B&Q, I get the next lot from Wicks although I will go into B&Q and try and get a refund.
A quick question does anybody use a boot seal (like door seal but rubber loop sits on top of U fitment section) on the front and rear storage bins. I think of getting some, as water seems to get in both sections , which is a bit of problem at the front as there are no drainage holes, yet. I am also hopping that it will provide some tension to the front Clam to make it easier to open.

I don't know what the K3 is supposed to have but my Mk2 came with exactly the type of seal you describe for the tubs. So far I have only fitted the front end and with the seal fitted and bonnet on minus headlights there is daylight at each side between the seal and the bonnet Pressing down as hard as I can on the bonnet doesn't completely seal the gap so I'm going to mark where it is with a marker pen by sticking my hand in the headlight opening (you can't see the gap from below the wing) and fitting a strip of flat sealing foam rubber from Car Builder Solutions to the underside of the bonnet. I haven't tried the back end on yet but no doubt it will have to be fiddled with as well.

My K3 had that on both - I never saw anything get wet in either 'boot'