Changing the motor in this case is the same as swapping in any factory option motor into any car, after the invention of Electronic Fuel Injection. You need the following:
Motor
Transmission
Engine wiring harness
Transmission wiring harness (where applicable)
Engine Control Unit
Appropriate exhaust system
Appropriate motor mounts
Rarely, a manufacturer will also have different driveshafts depending on model, or sometimes things will be drastically different (I'm looking at you Isuzu). Other times, you don't even need anything behind the motor because that's all the same on all the different models. (I love you Nissan)
For the Jeep, I know I need the 5.2, its mounts, its tranny, its wiring, and its PCM. That's all that's required. That said, I'll also be using its axles (3.73, possibly a rear posi, versus my open 3.55s) and I'll be grabbing a few bits from around and inside the parts Jeep as well. I figured I'd get a whole parts Jeep because it'd cost the same as just finding a motor from a Dakota or something.
Anybody into sport coupes from the 80's and 90s? I'm trying to find something I like that has 5 speeds, 4 cylinders, 3 pedals, 2 doors, and 1 low center of gravity, and while I came from that scene, I don't know what I like anymore. I've recently discovered the Ford Sierra was imported as the Merkur XR4Ti and that has me interested, but the only guy in the state that has one has a fairly lame one, especially for his asking price. Any ideas beyond the whole S13/14 vs RX7 thing? I've already done that.