Have a look through my notes on this page.
http://stweb.peelschools.org/sssweb/TTI-WEB/cars/projects.htmlI made the adapter, flywheel and modified the clutch for an Audi 016 (5000) transmission.
You need some key measurements;
1) Flywheel flat surface to transmission mount surface (Audi 90).
2) Audi 90 flywheel diameter.
3) Pilot bearing location (depth) into flywheel.
You might need the starter ring gear from an automatic transmission to make it work too. If you use the 850 flywheel your adapter plate will be spaced about 2 inches from the engine. I have a ring gear if you want it.
I have a clutch supplier here in Canada that can increase the clamping force on a pressure plate. He can even install two diaphragm springs if you want. I just had my flywheel resurfaced, pressure plate rebuilt and friction disc resurfaced with Kevlar for $425.00. About $200.00 cheaper than a rebuilt Audi clutch from NAPA.