For most any engine, racing or stock, this is the oil pump of choice to use.  This is the "Flat Cam" type pump, for use with aftermarket camshafts, or with stock camshafts for earlier engines. The 26mm gears are larger than stock, so they supply better oiling than the original ones for better high RPM use, or in a stock motor.  Don't make the mistake of using too large a pump, as this will lead to overpressure, bypassing the oil cooler, overheating, and leaks.  This pump is the perfect size, from mild to wild.

It is used with cases that have 8mm oil pump studs and the "Flat", (3-rivet), or aftermarket camshaft.  If you have a dished (4 rivet) cam, or an older case with 6mm studs, you'll need a different pump.