What would be different about swapping an OBD0 B16 into a 89, rather than a 90? Would the 89 be harder? Both cars are SIs.

story though, I have a friend with a pretty nice CRX with new suspension, as well as a ZC motor in it, and he's trying to trade it for my Stock SI with shitty suspension. His car runs a lot better than mine, he just wants the 90 because it's "easier to put the b16 in" because of some wiring thing? I don't know much about it, I was just wondering if anyone had any problems with an 89 that they wouldn't have had with a 90?