IF and i say IF the body / interior / mileage is true, and its really that clean. you really didnt get taken that bad. just drop in a rebuild and use the truck. for a running truck with 67k original in a "mint state" would value at like 4-5k. let it be a lesson learned that you never ever take the sellers word on a car. always do a thorough inspection.
i bought one of my old beater trucks it was a 99 denali for a steal. truck had been sitting for 2 years un touched. before buying it i started it up to discover a knocking noise but noticed the oil was empty. figured it was sitting so it got drained before letting it sit. figured the noise would go away with some oil. wrong, it never did not even with 20-50 lol. but lucky for me the motor ran for 2 years like 30k miles making 5 psi at idle. traded it in before it got worse.