90 Sunbird: engine swap possible?

I have a 1990 Sunbird that had a 2.0L engine in it. Are there any other engines from say a Cavalier or something that it would fit into the car and work without having to change the wiring harness and stuff?

Why do you want to change the engine in the first place? There are lot's of these engines around and the wiring harness isn't too big a deal to change should you decide to do a swap. The 2.8 and 3.1 liter will fit but the 2.0 is the better of the three.