First problem: It's an automatic... So you pretty much have two engine options when it comes to automatics: B18B1, which should already be in the
car, and the B20B/B20Z... Which is little more than a larger bore B18B1 that makes exactly the same power. Only reason to swap to a B20 is if your engine is blown. They're dirt cheap and a nearly direct swap.
These
cars make shit for power with an auto trans. Years ago, we had a member with a fully built and supercharged auto... It barely made 180whp. Best mod you can start with is a 5 speed swap.