As a disclaimer I haven't finished the swap yet. I'm still in the middle of buying parts and continuing to research. It's
a lot to learn.
If you want a shortcut without doing a lot of reading here is what I personally found to be a consensus on multiple forums. Get a GM engine, specifically the LM7 5.3L. It has a the aftermarket support you'll need and is the most commonly swapped engine in TJs with tons of builds/questions/info online.
I'm going the automatic route and didn't do any reading on the AX15, but I would venture to guess it will still push everything back and you will still have to change both front/rear drive shaft lengths. I would also HIGHLY recommend changing out the Dana 35 rear axle you have as suggested above to a Dana 44, ford 8.8, etc. Maybe you can get by without it, I was planning on keeping mine, but found out it was shot anyway and after doing more reading was glad I wasn't
allowed to use it. If your Jeep plans on seeing the trail I would advise you do yourself the favor of dumping that Dana 35. Plenty to read on axles/gearing alone.
If you're serious about doing the swap get ready to spend some money. I'm budgeting for around $15k and that's me doing everything except changing the shaft in the transmission to match my transfer case splines. I'll end up doing a writeup on costs when I'm done.
A short build list and not AT ALL exhaustive:
Novak is a good place to get general surface level info on swaps. Anything you can't answer from there and Google will be your friend. Novak, Advanced Adapters, and Holley are all common places where people get their adapters/parts.
Lastly, if money isn't an issue you can get a turnkey engine from companies like
BD Turnkey, ready to swap axles from
ECGS, or you can really blow your wad on a
crate engine. It's all up to you at that point and what you're trying to accomplish. Best of luck. It's been fun for me so far and I haven't regretted taking the leap yet, but my wallet fucking HATES me.