Here was one in California, maybe close to your truck's condition body wise, but stock underneath - it went for $6000.
http://www.cars-on-line.com/58231.html
A Restored STOCK truck brings $19,500 or best offer.
A rodded truck with a 350 in it also brings $19,500 or best offer.
http://www.cars-on-line.com/59023.html
In looking at your truck, the shape of the bed corner and the mess that you have there to begin with - $4,500 to 7,000 tops. You are really paying her for what has already been done: The crate motor and the tranny (if they work.), steering column, gauges, wheels and tires. That magnaflow exhaust wasn't cheap either. Is the frame done - as in all new bushings, brakes, paint and body mounts? If so, that truck needs the body work done, paint, glass and interior.
Be a great truck when done. I see Dolphin gauges, an Ididit steering column, newer wheels and tires, Corvette style master cylinder....if it moves under its own power, steers and stops...you have a great start there. Parts are easy to get and the truck is straightforward enough to be an easy resto.