question on Ignition

I can't imagine what would cause repeating ballast resistor failure.
If you're going to upgrade... install a relay. It can and should supply full 12 volts to ignition system, charging system, and electric choke too if present. The load through ignition switch, resistance in OEM current path, etc.. no longer concerns. The OEM wiring was minimally adequate for the 36 amp closed field alternator and accessories when it was brand new.
HEI ignition system and other modern electronics at one end, 60+ amp isolated field alternator at other end, aren't the upgrades they could be without a adequate current path between them. Relay creates a new and more direct path.