The heads had a previous valve job with poor workmanship. The guides were beaten in and all bent on the top, the valves were ground so there was no margin left on the edges. I blended the pockets under the valves as there were sharp edges. Got new guides, and valves. The new guides will be bored out for bronze inserts, and positive stem seals installed. All seat and stem heights matched. Springs shimmed to proper installed height. The shortblock looked great. It was a combination of crappy gas, and poor workmanship that stuck three valves.