You'll find that less is more if you talk to folks that will be honest with you.
An R6 will keep you so busy, you'll be riding 15 drag strips on B/W and trying to get thru the corners without lighting up the rear tire.
I suggest looking in the classified of the Bay Area Riders Forum (. ) for a race prepped
Kawasaki 250 or 350 Ninja. Not a Formula 250 but a Production 250 that has reworked suspension and is already prepped.
A gen 1 or 2 Suzuki SV650 Production would be another excellent choice.

Avoid the Formula bikes as you want a motor that hasn't been built or tuned to have a short fuse.
Either of these bikes with a stock motor would be a ton of fun and run forever.
Then get a suspension guy such as Dave Moss or Catalyst Reaction to set the suspension up for you.

Most track day providers have a guy onsite that will do this for a reasonable cost.
If you can find one that features a school , not just a trackday, you'll be money ahead.
You can also attend California Superbike School .
Pridmores CLASS school may not be a good fit as they teach a street line on a track.

Classic Cycle Connection
1971 R75/5 roadracer
1973 Kawasaki Z1 roadracer
1976 BMW R75/6
1999 BMW R1100RT
2007 Kymco People 200S