Dont know about the short bodies ( :embarassed: or what they are to be honest) but a 16v will bolt straight into a mk1 gti with the mk1 engine/gearbox mounts fitted to the 16v (i'm in the process of doing this at the moment
http://www.golfgtiforum.co.uk/index.php?topic=35338.0 )
you'll need the engine loom from the 16v which is pretty straight forward to wire in, then you've just got to worry about the exhaust - either buy a 16v mk1 4-branch manifold (about £330) or fabricate your own downpipe using the mk1 pipes the 16v flange to the manifold and some random bits of tube to join them together (i should have pics of mine on monday, providing it doesn't rain too much over the weekend & i get a chance to do it)
You have 2 choices with the gear box, mk1 or 16v (mk1 better acceleration/16v more top end) and you 'll need to use the clutch to match the gearbox (190mm or 200mm)
driveshafts are a bit of a grey area, i depends on which gearbox you use & whether you can be bothered to swap the drive flanges - late cabrio or scirocco ones seem most popular.
pm me if you're going ahead with this and i'll email you loads of info i have on it
