oil pressure and crankcase pressure

Even if the block passages are plugged somewhere, the relief should dump pressure directly back into the pan. I vote for screwed up relief.

By the way, how much is "too much"? My old 340 used to run "too much" I.E. routinely pegged a 100 psi SW gauge. I never perceived any problems, and never blew out a filter. I do realise this was a few years ago, filters "may" have been a little better then. Wix. Always, Wix.