I bought a 1999 GSXR 600 with 300 miles on it back in 1999. Was putting it in the car when Yamaha came up with the R6. I took the GSXR out and put in in a box and set it on a shelf, best move I ever made. That R6 changed everybody's idea about 600cc motors back then. Kawasaki came along and made it Old School.
Best I can remember back then a lot of 600 and 750 GSXR part interchange I think they just changed the jugs.
Honest Dad himself