I went thru oil pressure issues years ago with my solid roller cam motor. It had high bearing clearance. Mains and rods were around .0038. I tightened up with .001" under bearings. It did absolutely nothing for oil pressure. My engine pushrod oils. Turned out the pushrod feeds were .090". Tightened them up with roll pins to aprox .050". Night and day difference. internall leaks will overcome low volume. Once its hot the pressure is low. Either tighten the leaks. Or add more pump volume. In my case the bearings didn't leak enough to make a difference.
Doug