Thanks - that gives me something to start with. As you say, the HIF44 is big enough but as I'm trying to give my car the retro look I couldn't resist the HS4s
Anyway, my HIF was very badly corroded inside when I got it and although I've rebuilt it twice I'm still not happy with it because it loses all the oil from the dashpot within minutes of starting the engine so I needed to buy something else anyway.