I don't know about SBF's, but I had a ton of trouble when some genius engine builder put a HV pump in the 327 in my Corvette. Smoke on startup, pegged oil gage, fouled plugs, excessive oil consumption, etc. I finally solved the problem by installing a stock replacement pump. Seems all of the oil being pumped to the top of the engine was overwhelming the drainback system. The guys who designed these engines knew what they were doing and provided the optimum pump fotr the application. Use of a HV pump in anything but a racing engine with opened up clearances is folly. If you check the suppliers (Jeg's Summit, etc.), you will see that the HV pumps (for a SBC anyway) are half the price of a quality standard pump. It seems some of these engine builders can't resist "upgrading the build" while saving a few bucks.