Last year I swapped in the drivetrain from a XJ into my YJ to replace the angry squirrels, it was a great swap. However it still is a lot of work and just to point out, the 4.0L drivetrain is longer than the 4 banger, so your rear shaft will be SHORTER. Therefore you will probably need a SYE kit and a CV shaft or a motor mount lift and t-case drop.
As for the XJs with 44s, I believe the most popular is around 87-88