Pulling and replacing the existing ECU should take 15 min the info (part number) is on the sticker.

Do you have a way of reprogramming the used ECU? It’s not going to work unless you can have it reprogrammed to your VIN

If you purchase a complete set of electronics from a donor and change all , it will work.
ECU
SKREEM
Keys
ignition
BCM

buy a used ECU, without the ability to program it and it will sit on your bench, Forever