I took a 2.4 out of a 98 sunfire gt, and put it into a 97 cavalier z24. i figured everything would be 100% compatible, no issues. and for the most part it was.

It may seem common sense, but mark EVERYTHING you disconnect. put bolts in bags (intake, exhaust, Power steering, etc.) I had to let the car sit for a week between the time i removed the engine, and the time i dropped in the new one. The electrical connectors are fairly cut and dry, as the harness only goes so far in certain spots, and no 2 connectors in the same area of the motor are the same. mark those starter wires. i had to look at the schematic to determine what went where.

I don't know if this is a case by case issue, but the sunfire had a different oil pressure sending unit than the cavy did, and the sunfire had a oil level switch in the oil pan, whereas the cavy did not.

also, while its out (specifically a quad-type motor) replace that thermostat. if you've ever had to do this on car, you know how much a pita that can be.

last, make sure you do the crank variation relearn procedure. normally, you do this anytime you replace a crankshaft position sensor (ckp), or in the rare instance a crankshaft. but considering you are putting in a totally new (to the ecm/car) engine, the ecm is calibrated to the last crank & sensor pair. if you do not do this, the ecm may not be able to properly diagnose a misfire issue. so you could get a check engine light, and have nothing wrong if you havent done this. (note: on the cavy, its a dealer thing. need a tech II scanner).