72 chevy 4x4 longbed, worth ??

[wjr]

heres my delima, found a all original 1972 chevy 4x4 longbed,its an a/c truck and all the componets are still on it, compresser condenser and such, it is a 1/2 ton, with automatic, small block motor. it has had some prvious repairs done to the body ,but now have come back. the truck has set for 3 years now cause of a death in the family. so dont no anything about the motor and trans and such . cause the fellow that passed is the 1 who owned it and noone in family knows anything on it except that they want to sell it. i would like to have it but just dont want to cheat them nor myself. the cab supports have rusted out, there is some rust in the center of bed floor over 1 of the supports,the inner cab corners have rusted cause it has the famous expandable foam in it. LOL. dash pad is gone and someone has busted out the back glass. ?? why, but anyways the radiator support from what i can tell has some rust but the inner fender on that side doesnt look that bad.
But it is complete a/c all together truck.

my question is what would be a rough estimate of what the truck would be worth as is ? like i say dont want to cheat them nor myself. any advise would be helpful