Mike, this baffled me also so I called the guy who has my cylinders and he told me none are beat up like the piston. As for engine history, the only thing in the log book was an entry back in 1991 that documented a major overhaul. The Hobbs on the plane was at 410hrs total time. The engine was installed when the plane was built in '91. It set up for many years, thus ruining the cam, lifters, and accessory gears. I know this damage couldn't have happened when I test ran the engine. Too much old carbon build up on top. The funny thing is that during the pre buy, I cranked the engine to check oil pressure and mags, pulled the plugs, checked compressions, and did a visual on the oil. All looked good on the surface. I'm just glad I discovered these problems on the ground rather than at 100ft on takeoff.