oil pump question ?

Higher volume pumps are not necessary with a stock pan in an engine that won't see hi RPM very often. Seen as many running Hi-volume pumps just fine on the street too. Overkill, maybe, but probably better to err on the side of caution than to need it & not have it. I've built a few & seen many more street engines that are just fine running a stock pump.
High volume pumps are an advantage when you have looser tolerances in the motor(as a race prepped engine would) so the added volume in the pump can maintain the desired pressure. It will only produce as much pressure as the relief spring will allow thus regulating the amount of oil pumped. The added pump volume also helps to prevent cavitation in the pump at higher RPM.
So the real question is can you get by with a stock pump? If you already have a good Hi-volume pump in it I'd leave it in there.