Well I see a lot of T500 activity just recently so I guess I might as well present my T500 project!
I just picked up a 71 T500 with a 76 motor in it and it looks like the forks are from a GT500. It's a bit of a mess but it does run just fine, paid $600 for it, not sure if thats a good or bad deal. This will be my first bike build project and I will be doing it with my 16yr old son.
Here is the plan so far:
Frame mods to suit mono shock rear, possible geometry change to rake angle, frame bracing.
Use modified FZR swingarm and shock/linkage
Kawi 636 front forks
Run 17" spoked wheels from my KTM supermoto
Fabricate new gas tank, seat pan and tail section
Oil tank under seat hump
Build my own expansion chambers
Totally rebuild the motor and port it while its a part.
I am sure there will be changes along the way but that's the plan as it stands. This is a long term project as I have very limited time avialable so updates will likely be few and far between.