Anything above 60 psig is a waste and depending on where the
oil pump RV is set in the
oil pump may be just dumping back to the pan creating heat.
I suggest 10W30 if you can get 55-60 psig at 6K rpm. Long story but I had a stroked 351W that had 42 psig at 6K rpm and never did a lick of damage to anything.
For each jump in viscosity at 100C you gain 5psig
oil pressure, so 10W30 vs 10W40 is 5 psig than another 5 psig going to 20W50. I ran the living sheet out of my engines and ran 10W40 and had perfect oil pressure. I also noted the higher viscosity oil like the 20W50 the oil temp ran about 8C hotter. It was always at 100C where 10W30 was at 85C and 10W40 was at 90C water temp at 88C