If you have ever used a factory oil cooler, such as the one I added to my Diplomat, it's essentially an internal leak. It taps off the port where the sending unit goes, feeds thru the cooler and dumps back into the crankcase thru a rifle drilled fuel pump bolt. My oil pressure never hit the relief spring rating, I added a good oil pressure gauge, too. The HV pump had no problems keeping everything lubed. Used the stock drive too and never had an issue, till it sucked up a bit of cast iron and locked the pump up, my fault there I modified the screen to "open it up" and it sure did open up.

As for fitting an HV pump on a smallblock, I usually test fit the pump and pan without gaskets, use a torch to spot heat the pan and a hammer to clearance it, then the gasket will space the pan up enough so that there is no rubbing. works for me.