The AW4 appears in Toyota Pickup, RWD Van, Celica, Supra, and RWD Lexus (which is just an overpriced Toyota anyhow.)
The XJ/MJ/ZJ version of the AW4 features an extra friction plate in each clutch pack to handle the loads that are more expected with trucks (towing, pulling, and the like.) This from a comparison of Toyota and Jeep parts catalogues.
Upon further reading, the NSG370 gives a "low" first gear of 4.46:1 and a Reverse ratio of 4.06:1, with a single overdrive (16%) and a "direct drive" fifth gear. The concept is sound, but the first gear could stand to be lower.
Also, I do now know what the bellhousing pattern on the 3.7L V6 used in the KJ is, so I'm not sure if it would fit. That's something else I plan to address when I finally get a line of communication open with DCX (Archival Tech.) If the 3.7L V6 and 242ci I6 do not share bellhousing patterns, then it falls to either make an adapter plate or cast a new bellhousing, if it is removable (given the current trend in manufacturing, it probably is.)
Now, if they'd given it a "granny first" in the range of 6.0-7.0:1, they'd be on to something. The SM465, as I recall, was a "1+3" box, with a low first gear down around 6.6 (or so):1 - you drove the thing like a 3-speed on the street (using 2, 3, and 4) and used 1 when you needed to pull a stump or something like that. With a dead low first gear, the NSG370 would effectively be a "1+5" box - driven like a five-speed until you need a low gear.
However, the relatively high overdrive may be more useful than the 25% or so overdrive found in the AX-15, given the trend in gearing. An interesting possibility - I may have to crunch some numbers later this week...
For those interested - 1/2/3/4/5/6/R"
4.46:1/2.61:1/1.72:1/1.25:1/1.00:1/0.84:1/4.06:1