While I'm not disagreeing with the pickup to pan clearance being a problem, if you're seeing a constant 50 to 60psig oil pressure then the pump is getting suction and pushing oil. If the volume of oil flowing was dropping then the pressure would be dropping, too. I think you're dealing with a restriction, especially considering that
He disassembled engine and looked at all bearings and cleaned all parts.
which says he didn't have the block tanked by a shop, but simply took it apart, cleaned things up and put it back together with new parts if I'm understanding you right.