Thanks for all the info and suggestions folks. We will be following them up. I had forgotton about Mal Wood. He might be able to source a box for us. Looks like a 3.45 to 1 ratio might be the go. We dont want to go a whole lot taller since the car is more of a cruiser than a strip machine. The overdrive 5th in the T5 should help anyway.
I had also forgotten about the different 1'st cog ratios in the V8 and 6 cyl T5's. I looked the ratios up in a workshop manual following that comment.
I knew about the ATF for a T5. I found out when I changed it in our EA S. It's amazing how many people get it wrong though and then complain about shift quality etc. I was also a bit surprised that the old single rail 4 speeds use common engine oil (at least that's what the book said for an XD).
I guess the only other question is will the T5 handle the extra grunt? We are not sure what the motor will pull but it is being built for strong mid rev range performance. The engine builder is aiming for around 400 flywheel hp. I'm guessing the box will be a bit marginal.
I take your comments about the clutch setup. I am a bit loathe to go cable but that is what we were originaly told would have to happen. If Dellow makes a suitable bellhousing it will save us having to change the pedal etc. Does a T5 have a different sized / splined input shaft ? The current twin plate clutch is in good nick and if it can stay - all the better.
Anyways - thanks for all your input. This is a great forum that I follow religiously.
Per your request - I have hastly thrown a page together here : http://athene.csu.edu.au/~psproule/aps351
. I don't have any more pics but next time I am with the car I'll take some.
Regards - Pat Sproule.