i'm approaching the end of my break-in period, and i've managed to be very responsible. i haven't wound the cleveland any higher than 4k rpm (and then only briefly as i approach a shift) and have varied my driving greatly. when i complete the break-in, how high can i safely spin this thing? i'm not talking about sustained rpm's, i'm just talking about winding it up and then shifting. the sound of the motor at 4k sounds like it's screaming...i can't imagine what 6k sound like. the motor is a 4v with closed chamber heads, stock valves, comp cams 270h with matching springs/timing set/lifters, stock rods/bolts/crank, clevite bearings, kb hypereutectic pistons, and no oiling mods other than hv oil pump.