Which Ignition Box Do I Need

sounds like a distributor problem? you describe the marbles sound. that's pinging(spark knock). BAD SOUND. you're total timing is too much. you need to tighten the advance curve down to somewhere in the 21* range. my old mp distributor had 29* of mechanical advance. it was horrible. consider you want around 34-35* total timing - 29*, well thats only 5-6* inital. horrible. you need to weld something in the plate area to lessen the amount of centrifugal advance.