I bought a 79 stepside about the same condition as yours.
I changed the box, cab, doors, fenders,inner fenders, bumpers, hood, interior, motor and transmission.
The chassis was surprisingly in great shape.
Put about 25 G's into it and sold it later for 9.
So yeah, I always lose on my rods. My latest project which I paid 4000.00 for will get about 40 G's into it and will maybe be sellable for 25.