Rebuilt engine initial fiasco

FWIW, the oil pressure regulation is before the filter, and the filter has a bypass funtion that routes oil past the filter element with more than about 8 psi of drop in the filter. So if you had 60 psi on the gauge at 1600 RPM, then I suspect you would have no more than 70 psi into the filter; the gauge is measuring right after the filter. Take off the filter and adapter and look at the gaskets and see if there is any distortion on the fitler base gasket; that is one sign of excessive pressure.

My issue with the 20W50 is that it just is NOT gonna flow as freely when cold as will a lighter weight. You need it flowing copiously to the cam and lifters.