I don't really want to drag this thread off topic, but since your question has been anwered, are you going to be running on the stock NA internals? The last I read about them the ringlands are very close to the piston crown and won't hold up to much detonation, considering that's the usual cause of failure of the stock cast pistons, ringlands cracking. What are you going to be doing with this engine? As long as you avoid detonation at all costs it should be ok, I guess.