Heck I don't know, when you blow near 2K just for a new evap. & condenser, rebuilt POA & Expansion valves, hoses and dryer, seems to me everything is going up. Sure, "I can probably restore this truck for 18K"

That might get you paint.
If I were to guess a running 67-72 runs anywhere 4-100K, with fair "restorations" or low miles in the neighborhood of 25-40K.
Having said that, I get Craiglist hits and geezuz the stuff that comes up. Most recently a modified (cough!) 67-72 4WD with dents for 30K.