Does someone actually make a torque tube adapter?
The only one I'm aware of is the one Patrick's sells for putting an iron Saginaw 4spd into the 48-55 trucks.
My guess would be that any late model tranny is going to be too long. Not to mention the bolt pattern and input collar size are probably wrong, and maybe even the input shaft length. You would also still be stuck with mechanical brakes. Rather scary at 65+ I'm thinking...