want to convert a f440 to f600 for autocross

I have a KBS MK 4 with a Kawasaki 440 that I want to convert.



Anybody got any leads on a F600 motor? Most interested in reliability over perfromance.



More interested in fun than being uber-competitive and I am only interested in autocrossing this so I don't need the latest motor - any 03 or later Suzuki GSXR 600.



Any tips, tricks or advice would be appreciated.