[cetacean6]

I'd need to see the condition of the metal. I'd want to see how the roof and floors look, because if both front and back are shot you're looking at either getting 2 donor cabs (or 2 patches) and/or doing a bit of fabrication work. If the pillars are shot, that's a lot more.
This sounds like it would be a good candidate for a custom truck. Find a later model chassis with power steering and brakes; add a C-notch and bags, then drop this cab on there...could be nice!
Just from what you've said....I don't think I'd go above 750 to 9 hundred on it. If the metal is in good shape, maybe a grand. But that's just my personal opinion. Would love to see pics!