Done by Yoshi ('95 RF6/9):

Putting in the 900 motor was a sinch.  The two RF's share the same frame...exactly the same frame.  So all there was left to do was drop my motor and put the 900 in.  Of course it necessitated changing the ignition box, coils, and hooking it up to my wiring loom.  All in all, a very simple task, I'm very suprised no one else has done it(to my knowledge).