CM871 OIL PRESSURE

[untouchable]

The unit has always had 40 psi of oil pressure at start up cold and would stay around 30 at operating temp also. the customer started it and found it sitting at 30 psi at start up then dropped to 15-20 after warm. the last rebuild was 200k miles ago, we found cam bearing wear, cam wear on the valve cam, rods and mains worn. all parts are aftermarket execpt for the oil pump. the oil pressure has not changed after we replaced the worn componets. we are at a loss of what could be the next step on correcting the issue. we understand that the oil pressure is in spec for cummins but the customer will not accept the oil pressure being under 20.