Copper coat is a sticky glue like spray with fine copper pieces mixed in. The idea behind it is the small copper bits work there way in to the small pits and machining marks to seal off the small leaks. It works really well. It sure won't hurt to use it, but with a good paper faced gasket like the Fel-pro's, you shouldn't need it.
Just how long have you been driving the truck before it got hot? years, months, days?
I have seen guys wipe oil across the whole head surface including the chambers and let is set for awhile. Then go back with brake-cleaner and wipe it off. You could see the oil creep back out of the cracks once the surface was clean.
Joe
