Fronts of the frames are not the same; the D50 ttb (Twin-Traction-Beam) is not a bolt-on on the F150 frame. Pivot points are different and the F250 uses leaf springs vs. coils on the F150.

I'll fourth the idea of swapping the engine and sheetmetal onto the 3/4 ton frame if possible. If the F250 frame is bent from the wreck, you can convert your F150 to 4wd using the transmission and t-case, but you'll have to find a D44 ttb out of another F150 or Bronco from 80-96. That axle assembly will actually bolt in place of the Twin-I-Beam 2wd front axle you have now.

And if you just want to (like myself) you can swap in the Sterling 10.25 rear axle from the F250 and convert the D44 ttb to 8 lug using chevy hubs and spindles. At least the drivetrain would be 3/4 ton if not the rest of the truck.