I've always ran 225/16 and 245/16 tires on my flared 914. Typically 225/55/16 and 245/50/16 or sometimes 225/50/16 and 245/45/16. There used to be a ton of tire options and several good "max performance summer" tires to choose from. Now it seems there are 3 options in total for those sizes:
BFGOODRICH G-FORCE COMP-2 A/S PLUS
RIKEN RAPTOR ZR A/S
KUMHO ECSTA PA31
Fortunately none are that expensive, but also none are really great for a sports car never driven in the rain.
Or is there some place else to look? What tires are you running with 8" and 9" (or 7" or 8")?
-Steve