Anyone customizing there stock 340 Windage tray?

The problem here is a HV pump in a stock pan. Next issue is the oil pump itself. While many find a HV pump not needed, the passage at the mating point to the main cap and the main cap itself needs to be worked on and opened up. Much like a ported head.

The stock windage tray needs nothing more than the louvers opened up. But at your level, I'd opt for a new everything from Milodon. In which a road racing pan is excellent for the street or there drag race pan for just that. Depends on what you doing. Drag racing seems to be it. Driving the street any?

IMO, you were starving the engine of oil through high RPM's.

Opening up the passage ways in the block was good.