The 12 volt system allows for more voltage to the ignition while cranking, allowing more spark. You stated that you converted the truck to 12 volts. As stated, the resistor is needed to slow the burn on the points. But it is not necessary to wire that feature into the conversion. The reduced voltage provides enough spark.
I converted my 52 to 12 volts. Replaced the generator with a 12 volt alternator, left the 6 volt foot pedal starter and replaced the coil and capacitor, adding a resistor without a bypass circuit. This was over 50,000 miles ago.
