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Sorry for not being Johnny on the spot with an answer for you. I still work a day job! You got your answer already. It's very simple geometry and math. The generator pulley will turn the alternator faster than it needs to. I never said your rig wouldn't work but your alternator will last a lot longer if you run the slower pulley. Saves on bearing wear. Electrically speaking it can be a problem in more modern engines where RPMs run much higher than these old flatties turn to. Does this clear it up for you?
