[jonzcustomshop]

looks great in the photos!
however, those last few make me cringe....
It looks to be bondo/paint over old rust...
that is not good, bondo does not stop rust, just covers it for a while, and in most cases I think makes it worse...
I have a feeling that if you blasted this cab thay you would end up just looking for a new one...
I hate to tell you that, but that is muy opinion...
another thing about the rust...
in the 60's they did not treat the metal before assembly, the only treatment it got was the paint on the outside surfaces...so all these trucks-even the "rust free" ones are rusting from the inside out.
when you see bubbles coming through the outside of the roof rear door jamb, the inside is going to be way worse... like the tip of an iceberg is what you are seeing.

what i would do:
looks like a decent truck, drive it enjoy it, be on the look out for a decent cab and doors, when you find some, do some swapping.