understanding a low oil pressure 360

I asked in post 5 about clearances and what lifters. He didn’t check clearances and didn’t answer the lifter question.
I don't see how the heck anyone can help him until that's found out. I know a guy who built a slant six with standard crank bearings on a .010 under crank. It actually had "decent" oil pressure until it got the least little bit of heat in it, then it didn't have "much".