as far as I'm aware no one makes performance parts for the type 3
I had an early squareback years ago, and there were many new cars that didn't ride as good, kinda like a small odd german cadilac.
I think a nice set of adjustable shocks (may require some fabricating to make happen) and a beefy anti-roll bar front and rear, it could be quite a performer.
for anything beyond that
see here