85 gpz top end on a 80 "E" bottom.

I have a 85 gpz 750 engine , I see theres a difference on the cases of a 85 gpz and a 80 E..... question is- can the gpz top end ( cylinders, head, cam, cam chain etc.) be put on the E bottom? is it a case of off with the old and on with the new? the E is a good , so far, engine. just could use the extra HP of the GPZ. and no i cant "bore" the E to a 810 etc. i must keep a 750cc 2 valve aircooled limit. what will i need and do? i don't plan to do this now during the race season , but this winter. thanks in advance, T