Try searching on "AX15" or "NV3500" for a truck 5 speed.
75Slant6 put an AX15 in his Duster. Not an early A, but might be helpful. My Duster Adventures
I know there is at least one other that did it as well.
If you search on "R154", you might find more info as well. I started swapping an R154 into my '63 Valiant and there are some pictures online of what I did, but I will let you find them. Never completed it, car was too rusty.
You would have to run something like a 2.27 rear end gear to simulate a 727/3.55 setup. But that ignores the torque multiplication in the auto. Running a 2.93 rear gear with an AX15 would be like a 4.56/727 combo.