It has been awhile. As I recall, I believe the GSXR1100
engine fits into the GSXR750
frame. The frame is the same and because the engine cases are the same size, just bored to a larger diameter in the 1100, it is an easy engine swap.
But I think there is a difference in the lower engine
that makes it not possible to put the GSXR750
into the GSX600 Katana
frame. It may be that you need to fabricate new lower frame rails to accommodate the larger GSXR engine.
Your best bet is to check with the discussion forums at DragBike.com
. It has been my experience that anyone who has successfully accomplished this engine swap, would be more than happy to share their knowledge and steer you in the right direction.