Strange Cylinder Ridge in Rebuilt 340

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?

Need pictures... are they all at the height on all 8 clys?

I can't get my camera to take up close pictures that show the wear pattern. It's in all 8 cylinders at about 1 1/2" down from the top of the cylinder(lower ring problem?). The pistons appear to be installed correctly (notch pointing towards front of engine).

Any ideas?

Are you sure that it isn't just a ring set mark from not being run for a period of time and will disappear with a little run time?

could be a timing problem.