1959 harley cases. Bottom end is good. want to go with SS oil pump. have hydraulic lifters. will I need to drill anything to make the ss pump work right? what is the drilling for? I mean what passage does it open, what assembly does it provide oil or drain to? What have other people had success with? My basic problem is, I've got a new Accurate top end, and want it to last, so want more pressure, more volume than the worn, stock pump. Somebody explain, please?