I had a 91 GT and a 1994 XP. I don't see any reason why you can't swap motors because I think they are both the same physical outside dimensions. And since you have the whole 1993 XP you can pull the motor,electronics, pump, etc, out of it. The guy I got my 91 GT from put in an aftermarket rotary valve with different timing and a Solas impeller, for a 580 I think it ran good. But transplanting a 650 should be better.