1998/1989 Powerhead/Lower Unit switch

[woftam]

Hello-

I have a 1998 90 Yamaha with a bad lower unit. I am thinking about purchasing a 1989 Yamaha 90 with a bad powerhead, but a good lower unit.

My intention is to either place the lower unit on my motor with the good powerhead
-OR-
Putting the powerhead on the motor with good lower unit.

I need to buy this unit and want to know if the parts are as interchangeable as I think.

Please advise.

Thanks