Engine swap, how hard from a 2.2 to a 2.4 or 3.1 in a 95 sunfire

Just wondering what all I would need and how difficult from a mechanics point of view would this be. Im not doing it myself, im having a friend that always changes engines and trannys helping me. He said I will need a new harness and computer to go to a 2.4. Will I need anything else like different mounts and brackets and will it make up to my stock tranny without a problem? I was wondering the same about a 3.1 from an older z24, I heard people always talking about that on here and it seems like an awesome idea. If anyone has went from a 2.2 to a 2.4 or 3.1 lemme know what all was involved if ya could.

Thanks guys