BB 440 with a blower crank trigger ideas needed

I am thinking of doing a crank trigger EDIS system. Trying to figure out a crank trigger using the blower belt pulley and balancer not much room for a trigger wheel. Thought or ideas welcome. Seem like I seen somewhere a series of holes drilled into the balancer with one spaced hole and using a vr with the holes instead of a trigger wheel..
But not sure.