I am using a magnum 5.9 block, 4" crank, Iron Ram heads, eagle rods, ross pistons at 12 to 1 comp. Its in a 3300lb Volare running mid to high 10's at 122 mph. Been doing it for 7 years also. I did do a cam change a few years ago. Other than that, never taken a valve cover off it. Its a work horse! We guess its making arount 530 hp with no adders.