My gapless ring 340 is around 9.6 and it will give the odd rattle on pump...but that might be the extra oil it's burning.
I'm going to put new pistons in it this fall and will most likely go with flat tops like the one you used, I'm going to order a cam around the same size as the one you are running and throw it back on the dyno...I'm really interested in how close it these engines will be as they will be almost identical.
