The AMC 327 is a great engine; massive block, forged crank and rods. It's an excellent engine for a 1st-generation American V8. It will run and run and run if you keep oil in it, but it will cost a lot more than a Chevy to rebuild.
If you want to go Chevy, rather than buying an aftermarket adapter, find a Chevy case TH400 and swap cases. The Jeep engines prior to about 1974 used a Nailhead TH400 and a ring adapter for the specific engine. You have the opportunity to avoid the parts worries of the Jeep TH400 (flexplate and convertor may not even be available ... possible you'd need to send out to an antique car specialist for rebuild).
In 1974ish, Jeep switched to an AMC case TH400, then in 1980 changed to Chryco transmissions. 1980 is a watershed year, when lots of things are changed. Passenger drop switches to driver drop. New transmissions, new rear axle, new transfer cases. The Borg-Warner BW13xx (original Quadratrac) was gone, replaced by various New Process chain-driven transfer cases.
Lots of drive train changes over the years. Likely both related to the longevity of this platform and the corporate evolution of Jeep Corp, being passed from Willys to Kaiser to AMC to Chrysler. There is a drive train database here:
http://www.ifsja.org/tech/figures/db.html
There are plenty of older threads, here and at IFSJA, that would answer your questions. Additionally, there are several TSMs available free for you to read and download. Probably can't get up to speed fast enough to evaluate either of these trucks, but you could go to look at them, and research the questions they generate. At some point, you may come across the ideal truck and be sufficiently knowledgeable to make a purchase.