I have never done a Cherokee 4 to 6 but I been doing swaps for many years.
First do you homework. Read everything about your year Cherokee you can. Does a buddy have a Cherokee with a I6 (same year)? If so park them side by side and craw all over them looking for any difference. Or got to a used car dealer and craw all over one of his. Telling him you are looking to get one.
2: Try and get the hole Cherokee the same year as yours. Get one totaled in the rear end. Set it next to yours and have at it. Expect to do some real rewiring under the hood. Expect to spend more than you figured. Expect bolts to break. Expect it to take longer than you figured. When you done I want a ride