I made up an aluminum bushing to fit into the distributor hole, with a 1/2" shaft through the center and a tang ground onto the end. A shaft collar sets the depth correctly to engage the oil pump, and I've ground a 3-sided flat on the top to keep the drill chuck from slipping as the load comes onto the pump. It's adjustable for either 6 cylinder or V-8 by moving the shaft collar up or down.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!