if you look at the pump, it has no provision to pickup any oil from the mounting surface on the block which is why i said you cant use the hole in the block,, that pump will actually block it all off just bolting the pump on,, id block off the external hole but the internal hole is no big deal. put a plug in the one you dont use on either the cover or pump, though id use the one on the pump,, i think its easier to fill the rotors comming from the back side,, ive tried both with a single line to 9000 rpm and seen no differnce in oil pressures