With the HV pump an improved oil pump driveshaft is recommended for the higher load. The hex is hardened, the taper to the hex is radiused and the gear is pinned. Though nor common, the HV pump can fail the standard shaft.

As long as you have the correct shaft the only drawback is you loose one or two HP. I use one on a B engine with full groove bearings and performance clearances. It helps keep the hot oil pressure at idle reasonable with that setup.