Since the pin carries all the load of driving the oil pump, I don't think I'd want to take a chance on a spring steel roll pin- - - -too brittle. This is going to sound really shade tree, but if you drill out the gear and the shaft with a set of number drills until it's a very snug fit for a piece of a 20 penny nail, and then peen the ends well, there will be zero slack and there will be much less of a chance of developing slop in the distributor drive. The nail is tough, not hard, and it takes the shock of driving the oil pump much better than a hardened pin.
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!