Why for are you thinking of this?
The AW4 is a sturdy slushbox - the only one I've "failed" is the one that lost three bellhousing bolts (no, I don't know how it happened...) and the fourth one loosened. The input shaft and crankshaft were no longer coaxial, and the damn thing just seized up. I ended up cutting it apart - but most of the rest of the internals, and all the clutches, were just fine! The only real problem was that the forward planetary gearset had jammed.
Rebuild? I've rebuilt one for my wife's 89 Limited, and that was about 50K ago. There are a couple oddball tools you'll need, but they can be made with minimal effort and a little creativity. I think the "special tools" I ended up needing would have cost me about $30 all up - but I had most of the stock handy...
Unless you have serious blowby or compression loss, it's probably not even worth thinking about rebuilding the AMC242 - unless you plan to stroke it. Considering a stroker can be done with all OEMR parts (258 crank and rods, the rest is 242 stuff,) there should be no major longevity issues or parts fitment questions. If you're going to build it, stroke it and get extra low-end power.
I think it cost me about $300 to rebuild that AW4 a few years ago, and I haven't gotten numbers you can use on the engine yet (my prices would mean little anyhow - I get jobber on damn near everything, and do damn near all of my own labour... I'm also a firm believer in overkill...)
5-90