I know you have much more in to it and it looks qood. I'm going to say about $13,000 if no serious rust issues in today's market but I hope I'm wrong and you get much more.
Besides the front floor boards that I mentioned, the only other metal work that I can see it needs is the truck extensions or quarter extensions. Previous owner just painted over them, but they have holes in them and need to be replaced, again just lack of money.
I was also going to do a passengers side quarter when I re did the paint. The lower portions on that quarter are filled with bondo. No rust there, just damaged from what I was told.