I bought a rebuilt 340 to drop in my car until I get the original rebuilt. The engine was complete carb to pan, but I didn't hear it run. It looked clean, turned over fine and the price was right. I decided to replace all the gaskets before putting it in my car. After pulling the heads I found that every cylinder has a small ridge or taper about 1 1/2 inches from the top. No ridge at the very top. It's not enough to catch a fingernail on, but you can definitiely feel it. I was told the piston are .030+ speedpro and the motor has less than 1,000 mile on it. What would cause this? Is this something I can hone and still use?