I went through my catalogs and found a couple 50A systems, rotor - stator - regulator. The problem is that even though the S&S will allow Harley components to be used, as in their alternator, I have no idea what model or year the S&S motor requires. The Harley listings offer different part numbers by year and model bike, even for the aftermarket high output kits.
To bad there isn't a way to use an automotive type belt and alternator off the rear of the motor some place. That would open the door wide open to higher output devices, heated seats, electric heater, heated steering wheel, heated driving suit. You can see what my frame of mind is in right now. It's in the high teens F and lightly snowing, so heated everything sounds good to me.
I never thought about heated steering wheels until I bought my '13 Buick Verano and it has a heated steering wheel. I use that every time I get in the car now, what a joy to have warm hands...