31 PSI +/- 5 PSI is the factory spec on the Oil pressure. At 50 PSI, you're grinding the followers into the cam. Usually that results in cam failure within just a few hundred miles.
It sounds as if a lot of oil is staying in the top end of the block, meaning that the cam is getting plenty of oil - but possibly a little too much for the stock valve seals.
Check the pressure regulator spring and slug in the accessory drive to be sure they aren't sticking.
