AMC DID use a 727 transmission from 72-78 in cars behind the AMC 360 and 401, and in the Jeep full size Wagoneers from 1980-91. The GM TH-400 was used in Jeeps only from 65-79. 65-68 was behind an AMC 327 (yes, AMC, not Chevy!) with an adapter (Buick Nailhead bell pattern, also sold as a "universal" by GM as the bell was ~2" shorter and easily used with an adapter), 69-70 behind a Buick 350 (with BOP pattern), and then 71 and later behind the AMC V-8s (AMC bought Jeep in 1970). 71-73 engines used an adapter and the "universal" TH-400 case. In 74 AMC was building enough Jeeps that they had GM cast special cases for them (some late 73s may have these also). GM may have discontinued the universal case at that time, not really sure.
Internally, the AMC and Chrysler 727s are identical in every way. The AMC version uses an AMC specific case with the AMC bell housing bolt pattern though. So you'll need an AMC case to put the 401 in your Chrysler. The big Jeeps only came with 4WD versions, but you can use the parts from any 2WD version (Chrysler or AMC) to convert one to 2WD. The driveshaft yoke from a Chrysler will fit also.
You're also going to have to check on the engine mounts. I'm sure they won't just drop right in, but they may be close. Likely just slotting or drilling new holes will fix that.
To be honest, you're probably better off finding a Chrysler engine and selling the 401 to an AMC performance guy. They are in pretty big demand by AMC people, but not necessarily Jeepers. Jeep guys just want to climb rocks for the most part, and don't mind swapping in cheaper to build when they brake them Chevys. AMC car guys are a different story! Post that ting for sale in the AMC section of e-pages.com or e-bay and it should go pretty fast. Check completed auctions on e-bay to see what they typically go for. A lot more than most Chrysler engines! I have to admit, an AMC powered Chrysler does have a certain ring to it, but then I'm an AMC guy!!