I have a Powermaster 82016 6V Neg. ground on the 59AB in my '46 Coupe. It has 5000+ miles on it with no issues so far. I have kept the original wiring and regulator in place, and had the generator rebuilt for spare. Will likely change back to the gen. if the alternator goes south.
https://www.jegs.com/i/Powermaster/713/82016/10002/-1