Desertdog....YEP...in my granfather's balcksmith's shop they would lay the heads on a piece of 1/2" thick glass sheet to see if they were warped. The cooling and heating cycles(thermal stress)are very tough on an engine. On steam locomotives the problem is so bad that you leave them hot for as long as you can when they cool everything will loosen up and leak. I would say that a head check on a granite surface block with an indicator would be in order. Perhaps a bit of milling and a good copper head gasket might solve the problem...Where is the swap meet? Here in CA the big one is at Pleasenton, CA twice a year....I'm headed for Death Valley in a few weeks anything going on in Quartzsite.....Steve