Sounds like you have your work cutout. Looking forward to seeing what you do with the old girl.
The only part on the body that is going to be saved is the cab. the rest is scrap.
I am a bit new to these trucks, but why would you crap the rest of the body? It all looks in pretty good shape sans the dent in the hood. Is there hidden rustrot that's underneath?
H4 would be a limited slip 3.25 ratio. Also, they did put 2.75 ratios in the trucks. Was there an "L" on the differential tag?
Looks like it probably a 2.75. Nothing wrong with that for a cruising rig... They go down the highway really nice.