U can put any obd0 motor in for the simplest install. So a 1st gen b16a(158hp) or a b18a1(135hp) for a b-series, or d16a6(if u dont have an si, 108hp), d15b5/6(130hp), or sohc/dohc zc(120-130hp) for the d-series. There might be a few motors that i'm forgetting, but those motors should swap in the easiest. If u go with a newer engine, you'll have to run obd1/2 to get it to work, which can be a pain to do, and expensive if u don't know how!
Do lots of research before u decide. I went with a 1st b16 for my 89 crx si. It doesn't have a lot of torque, but the b18a i was looking at offered only 130hp and 121ft/lb torque, so it's not a big difference in torque(111ft/lb-b16), but a big loss in hp from the b16. I don't wanna run obd1 either, so that's partially why I didn't buy the b18. Plus, all the wiring the b16 requires is four wires that go into the ecu, that's it!
Hope this helps ya, good luck!