Thanks mate that's exactly the diagram I was looking for . Should both the vertical measurements on the right be 31mm? I'm guessing they should be but I thought I'd check as one 31mm measurement is 3 times bigger than the other. Hence what you said about the diagram being inaccurate. Also I assume these measurements were made with the block totally straight upright?

I've finally started the process of fitting an EFi Turbo into my Mk3 Cabriolet - I've been stripping it down all afternoon. Can't wait to get it back on the road with considerably more power. It looks totally standard from the outside so should be a good sleeper...