It all depends on what is good and what is bad. You need to take the engine apart to determine that. The head and block will need magnifluxed. one of those may be cracked and causing a vacuum leak and that may be the problem. Your camshaft, lifters, and pushrods may need replaced. If I were doing this for a completely restored truck, I'd replace as much as possible within my budget. If all you have to do is take it apart, clean everything, and put it back together with new bearings, gaskets,the cost of having the block and head magnefluxed and cleaned, new valves, and crank turned, then you might be looking at $2000. If you are taking it apart and putting it back together. Then you can start adding costs of things needing replaced, and the cost of labor if you are paying someone.
