yeah, i suck at explaining things and even more at drawing what i tried to show above is basically the same as making a keyway in the crank and driver but instead of a square key i use a round pin. much easier as you don't need to broach the driver. and yes, the driver seats against a shoulder on the crank.

set screws also work fine but can cock the driver sideways if it is a hair loose on the crank. on one engine i have a long 2" hub that slides over the protruding crank and because the hole came out a bit too large i used three set screws at the rear spaced 120 deg. apart to adjust runout at the front...


dave