FWIW, the ford 4R100 is an excellent transmission, and very stout in built form. it would also probably be a hell of a lot easier to swap in. however, i know you are aware of advance adapters, and i'm sure you can make anything work w/ enough money and time.

 

even a built 4r100 wont take a Cummins + big tires + added weight + offroading. Ive seen quite a few built 4r100's toasted from 7.3's

 

properly built, i believe the 4R100 could/would. i would take the correct clutch packs, stall converter, etc. however, the allison is a better transmission.