I'd say that you have to do some research on what the actual going price for similar TF trucks are selling for in Central Texas. What they sell for in other parts of the country is just fly in the sky ball part figures.
Still having lived in Central Texas I can say that just because it is a Central Texas truck doesn't mean it is rust free by any stretch of the imagination. You have to check it over pretty close before even thinking about tossing out an offer.
Critical parts such as the back doors and the area around the back doors mean a lot on a burb or panel.
I have to say one thing, your integrity has to have some value here as you don't want to be known as the guy at work who ripped off your female coworker by lowballing her on the price of the truck.
I did find one pretty well rust free no engine 58 truck in Laredo for 3500
https://sanantonio.craigslist.org/ct...868287902.html That might give you something to compare to.
It still comes down to actual condition (barn find has no added value) it just means it was somewhat under cover. Clear title that matches the vin on the truck and what you both feel is an honest price. I'd rather have coworkers thinking I was a tad crazy for paying a bit more than they thought an "old dirty truck" was worth than having them talking behind my back because they thought I had ripped her off and gotten over on her. Or if you decide to pass help her with figuring out a legit asking price so others don't rip her off.