oil pump selection

The engine oil pressure at mid or high RPM's will not be determined by the pump type but by the pressure relief spring; both pumps will put out enough volume to build the pressure past the relief spring setting at those RPM's so the engine will see no oiling difference between the 2 pumps.

BTW, there are 2 springs for the SBM pumps: mid 50's and low 70's psi. The higher one has slightly thicker spring wire but looks the same otherwise. Either one can be in either pump, and KK reports that the Mellings use the higher psi spring in both STD and HV types, so you very likely have the higher pressure spring in your M72.

The only place there is a difference in actual oiling is at idle to mid RPM's. The HV pump will keep better pressure there, and build it faster as the RPM's come up. But it is not a huge difference in the SBM pumps as the HV impeller is only 20% taller than the STD pump. So either one will work for most SBM builds. (Hence the reports of consistent success with both from experienced people.) Other pump types in other engines have much bigger HV sizes vs. STD, so info for other HV pump types cannot be applied generally to SBM HV pump.

IMHO, I'd use what you have unless you are running loose main and rod clearances for any reason; in that case, the HV pump will give better pressures at idle and low RPM. You have a good quality pump either way. And, I don't know that rollers take any more oil than non-rollers.