If you use ARP bolts on the main you will have to clearnce the pump where it sits above the bolt. I had my main seal leak 3 times before we found this. The 3rd time through we found it because the oil pump gasket blew into 2 pieces (half of which was sitting in the bottom of the pan) . Looking back at my build thread, I see that somebody warned me about this but I didn't catch it.