There is not pressure at the rockers. It's by design splash fed. If you think otherwise look close at the stamped rockers, how much they move, and the design of the groove.
High pressure is in regard to the relief spring choice. High volume is in regard to the fluid output via a he rotor size. The pressures indicated on the gage are a function of the oil, the pump, and the clearances. So the choice in pump needs to be made by the guy designing the package.
