fresh engine blowing oil filter o ring on start up

Just put a new standard Melling M72 pump on it and be done with it. I would never use a pump off an engine that blew up. I agree with some of the other comments and bet there was crap sucked into the p2 stock me and screwed up the relief valve.
I agree. Going to pick up a pump this weekend. An m 72 stock melling.