I would just pop the valve cover check everything and check the manifolds as well before tearing the whole thing out. I also have a head and manifold lying around. Most common part to loose seems to be the thick washers that hold the intake and exhaust on , they're only on the bottom studs so people commonly leave them off and as they are special they get lost and folks use what ever is handy. Can't remember if there is a pic a part in Prescott but there must be , parts could be had there........I know 3 or 4 rally drivers there and can't picture them living in a town without a pic a part.

Tom