Our hot oil pressure is set by the resistance to flow as seen by the oil pump. Our peak oil pressure is set by the oil pressure relief valve that hangs down from the block. It opens up at about 68psi.
That flow resistance is a product of the 4 routes for oil.
- Crank and rod bearings.
- Intermediate shaft bearings.
- Cam journals.
- Cam sprayer bar.
Too much gap in any one of those will cause low oil pressure throughout the system. So if you’re worried about oil pressure you have to carefully check all 4 possible routes.
Of the 4 listed, #2 can be fixed but probably isn’t worth doing. If #3 is a problem throw away the head. Or if it’s a Lemons car use some JBWeld and hope for the best.