Did it in mine. Theyre right about just buying a 5.0. Its cheaper and faster. I just really really wanted to keep my car since Ive owned it since I was 16 (11 years)
I dont know what people list, but its really: engine (assuming accessories, brackets, mounts, and headers are on it), ecu, wiring harness, exhaust.
My car already had dual exhaust, so I didnt need much. I reused my old diff (which was already weak for a v6, and eventually swapped for an 8.8 rear. The weaker your engine, the weaker your diff can be. If its a 200hp v8, I wouldnt worry about it.
Radiator and fan (fan had already been replaced once, and radiator was recently upgraded to an aluminum one due to coolant issues [holes accidentally drilled into it)
Original automatic transmission bolted up fine. Currently has 170k miles on it.
Original drive shaft
Original Alternator and AC compressor.
(94 gt water pump, water neck, hoses, belts, etc needed)
It will run on a v6 instrument cluster, tach will be weird (not important in an automatic) and I dont know about speedometer, I heard it will work fine. I know to keep my odometer accurate, I swapped out those bits which were the same.