I'm no means an expert....but I'll shoot (since you asked!).
There are quite a few variables at play:
1. I see the 'rust-proofing' underneath. I put that in quotes because I can't really tell if that was done to hide, done to prevent, or done with expert precision. People like to buy untreated because you can actually see the issues clearly. That said, there are plenty of well treated frames/undercarriages out there and this MAY be one of them. The body looks perfect so it's possible the bottom is as well.
2. 'Solid running vehicle for the age.' - this can mean a lot of things. My truck is 50 years old and runs better and cleaner than my wifes 2017 Heep (...ignoring the past 2 weeks, that is). Maybe that's what you mean or maybe you mean it stutters/sputters/tanks?
3. Stock? Not totally, but I'm not as brutal about that as some of these other guys are here. I do see original style MC, manual brakes/steering w/ drums, super clean engine bay, 286 6cyl, 3otT manual with original style shaft, is that an upgraded electronic choke on that carb? or just a new clean cable I don't recognize?
So price? Assuming the bottom is rust free and just prevented and the thing fires immediately and runs all day? You've got yourself a truck over 45k, maybe as much as 55k. That wouldn't drop in your lap, but you could get it.
Rough rider? Rust underneath with coverups? I think minimum with that body as long as it runs straight and drives well you've got 30-35k easy peasy.