my dad has a 84 RZ, and I can see a few problems you would have. Since the banshee motor cases are exactly the same as the RZ's, you may think that it'll fit fine. but most likely it wont. If you ever wondered what the raised area on the back of the cases that is cast in, but 'plugged', its where the RPM meter went on the RZ. if youve ever had a banshee apart, you'll notice that there is an extra hole on the clutch side above and to the left of the clutch basket, right above the kicker gear. That hole is where the rpm shaft goes in a RZ. if you wanted to use a RZ engine, you would have to fix/plug that hole in the back middle of the case, not necessarily the one in the internal clutch part. Another problem would be your exhaust. the RZs had studs coming out of the power valve jugs that the exhaust bolted onto, not just springs like the shee that came later. since the stator side cover is different as well, it may not fit in the frame to well. Just dont do it.