We just completed a rebuild on a 402 Chevy. Comp roller cam and rocker arms, ported heads and 10.5 pistons. We had the engine on a dyno producing 483 hp and 482 torgue. The oil pressure was at 75psi. We have driven the truck about 10 miles and did not exceed 3000rpm. The oil pressure has dropped to 30 psi and has a squealing noise. Any suggestions?