5500 Conventional ?s

[3QTRTONS]

The '69 "K" 5500 Conventional (as seen in my avatar) is a project truck that may have come to a point of decision for me.
I realize that, being a Conv. cab, the cab front is different - i.e., regular pickup fenders are not compatible.
However, is that, and (I presume) the flat floor the only differences? Will the doors fit a pickup? At last check, they appear to be in great shape.
Being in Maine, there don't seem to be many 'Heavy Haulers' of that vintage on the road.
I have not pulled the pumpkins to verify ratio, but research in the manuals make me believe that they are 7.20s.
The rims are cast - an exciting discovery - IF someone nearby were in the market for period 20s.
MANY questions for sure.
Guidance requested and appreciated.
This is the ONLY 'Heavy Hauler' I own and leaning away from advancing with this rig.