Surely by the time you have bought the bike and spent fucktons of money upgrading the suspension etc you would have been better off just buying a sportsbike in the first place. You can get an early R1 / Gsxr 1000 for little more than 2k I cant see your ohlins FZs troubling them much.
The last trackbike I had was an 04 ZX636 B1h (Cat D) with a rattle can painted fibreglass fairing. I paid 1400 quid and used it for 20 or so trackdays. I spent a couple of hundred quid on oil and filter service, new front pads and fork and shock refresh when I first go it. Then did 20 odd trackdays spending nothing but tyres on it. When I found I wasnt doing as many trackdays I sold it for 1500 quid to a frenchman who drove over with a trailer, paid cash and took it away.
I had a couple of newish road bikes at the time also but either of them would have cost me a lot more than 100 quid if I had lobbed it up the track.
I can only comment on some limited experience, I've had 5 or 6 FZS600's , but recently borrowed a 2004 FZ6 for a day
I have to say that suspension wise the FZ6 in standard form was a far better ride than the FZs600, obviously age may play a factor in this, but the FZ6 felt a lot more substantial on the road, didn't pogo half as much as my older bikes and gave me more confidence in the corners as it coped far better with the bumps etc
Only my experience and obviously subject to a lot of factors but the Fz6 is high up on my list for when I go back to a road bike again, especially now good ones can be had for sub 2k
Jonesy