Story is that the truck was parked when the brakes went out, and sat for 25 years before the engine was pulled. Bought it expecting just a core, but want to see what it's like before deciding how much it really needs. Today just pulled the valve cover and plugs, because I didn't have much time. Also going to pick up a leakdown tester and compare all of the cylinders before taking everything apart. If they read consistent, and relatively good, I may just try to fire it up. Concerned some water may have gotten in. Found some flakes of rust that look like they came from the inside of the valve cover. Vacuumed them up, then Kroiled the rocker shaft assembly to address the surface rust and free up the adjusters.