I'm thinking an F,M & J subframe will be too wide for that era truck unless you move the fenders out. I had to move the fenders on my 35 Dodge sedan, and the tires were close to the fenders on my 54 pickup with 7" squad car wheels.

When you said "minus t bars", does that mean you want a Mopar suspension without torsion bars at all?

Your going to be pretty limited to something available before 57, or something newer with struts. The early stuff had a pretty good kick up at the front wheels to provide suspension travel. If you intend on using the older stuff, I'd probably go with an original frame and leaf springs. Newer stuff tends to have the suspension above the frame, so their frames were level, or almost level around the wheels. If your thinking newer stuff, I think I'd look under something like a 1st gen Intrepid. They were boxed tube frame with all components bolted above the frame. I think the struts would fit under the fenders easily. Wonder what's under the rear drive newer Chargers and Challengers, you would not have to modify the spindles due to the front drive like an Intrepid. Gene