My first option is 327 or 350 but prices are way exploited compared to 305.
I've heard the ZF are fine trannys but the part prices are way more expensive than any other tranny (at least here in PTY).
And everything have to be imported.

Let's see what comes first, the 305, 327 or even the 350 that I want to have more than any other.

 

Seriously, if you are going to change tranny and engine, use the chevy drivetrain. Use the NP231C transfer case, same as ours except it fits the Chevy 5 bolt circle. Then you could swap the whole thing in much easier

 

I thought so at first, but it's a little hard to find a 231 from a chevy instead from a cherokee.

Doing some researching, I just know from a guy here in PTY who have a 1988 TJ 4.0 stroker and supercharger, using the ax15 that came with the car, 4.88 gears and 38" boggers, same stock tcase, front dana 30 with ox locker and rear custom dana 60 from currie with arb locker.
That rig is about 400hp or more, don't give a crap to the car, like he was on a destruction derby and never hve broke anything on the car, besides the engine that it has been rebuilt 2 times because of piston fusion by temp since he fitted the supercharger.
How many hp's from the 305, 250, 350?
Dude, I'm going with the AX15, same np231c from my rig and the old 305.

Thanks everybody for your help, ideas and opinions.

 

You will find the 231C in just about any S!). Plenty of them and the chain is stronger

 

That's right, my rig's t-case is a 231C too, the only difference is that it have 6 bolts instead the 5 from the ones on gm's.
Both use the same chain and it's proven to be a tough t-case and I've read that some people use it even on rock crawling and never break it.

The initial plan was to install a complete chevy powertrain in my rig, but I have to take seriously in consideration that a gm tranny could be longer than the aw4 or the ax15 and have to modify the driveshafts. That's why I'm going for the ax15, I don't have to modify any driveshaft and the engine will sit right on it's place with it's insulators and tranny bolted on to it.
I spoke to the owner of the modified tj and he confirmed it has never broke the tranny, just changing the tranny's oil when it has to be replaced and adding an anti friction to it.

 

Food for thought:
It's 2018 and a little old LS 4.8 is so much better than any of those antiques...
http://www.hotrod.com/articles/make-...0-4-8l-engine/

 

Nice!