A couple of years ago my throttle got stuck, at 7,000 rpms I floated a valve and bent 1 valve. All 6 pistons had the half moon inprinted on the top. I put a new head on it and it's still going strong, I never took the engine apart, I just sanded/polished the top of the pistons with emery cloth. The compression of my motor is 10.6 to 1, a l28 block with stock bore and stroke, a fully ported E88 head (stock cam) and a clifford intake with a Eldelbrock 4-barrel. So yes a L series valve train can float at or past 7,000 rpm...