my fairlane

my oil pressure goes away when i romp on it to like 4500 rpms. any ideas that might be a easy fix. I am sure it is losing oil pressure becasue the valve train get horrorably noisey. I did recently go through the engine. New crank, stock rods, reground cam, new msd distributor, new pistons and just regrinding the valves on the heads.
Is there a weak link in the msd disrtibutors maybe the end of it broke and only catches the the rod at low rpm's, because it does come back.
I'm irratated and at a loss

this is a 460 30 over

By the way the stock distributor was broken at the socket that went over the the oil pump drive rod.