The "old style" Mopar alternators are well known for poor output at low speed. "Squareback" are better. It turns out that some of the LOWER amp squarebacks are better at low output than some of the LARGER ones. I think the 45a one.
Powermaster are modified. I don't know much about them. Bear in mind that special regulators are gonna be hard to find on "that Friday" when they quit. STAY AWAY from "1 wire" in my opinion. Main reason is that the voltage sensing is on the "one" wire......so any voltage drop on that wire will cause the system/ battery to run lower. You need OVER sized charging wire on a "one wire"
In general most/ all more modern alternators are better at low output. MANY on here have done "Denso" conversions. People like Mancini sell bracket kits and I'm sure there are others
FRANKLY back in the day WE DID NOT WORRY ABOUT IT (Low speed light dimming). I came from a time........my first cars---------55-6-7 Chev and 60 Falcon-------had generators. When you are saddled with those old things, a little light dimming with an alternator is nuttin' LMAO