There's plenty there to work with, and worse have been brought back to nice. Looking at those lower cab corners you probably have a little more rust than expected, but not the end of the world. These F100s are strongly supported, so you might look at a reproduction upholstery kit specific to this rig, they're relatively easy to install and would go with the "preservationist" theme.

Like you, I get a kick out of some of the descriptions folks will use, especially in for sale ads. "Ran great when parked" is almost a standing joke. Might as well say something like......."Looked terrific when it was new!". Enjoy the ride.