#1. The main reason to convert to 12V is that "iffy" connections won't have nearly the same effect on the total system. This is a function of Ohm's Law... which is why all cars converted over from 6V. Remember, it's a Law of electrical systems, not a request
#2. The other "must have", even if you stay 6V, is to get one of the newer fully electronic regulators. I understand you get that with the "12V conversion", but it's always the mechanical regulators that end up giving the most trouble. The generators themselves are extremely simple and reliable.
#3. The biggest single difference between 2021 wiring harnesses and 1960 wiring harnesses is the addition of ground wiring. Absolutely DO NOT
depend upon the frame to carry electrical power. Frames carry engines; copper wires carry electricity. So new return wires not shown on the original harness diagram need to connect the battery
, regulator, generator, head lamp, tail lamp and accessories. That alone will eliminate 50 electrical issues !
Hope this helps.