The 2-unit item on the firewall with the fuses is a headlight relay- - - -one set of contacts for high beam, the other for low beam. It has nothing to do with the charging system. That was a very popular aftermarket add-on for 6V headlights because it took a lot of voltage drop out of the circuit and resulted in brighter lights.

The wiring on the cutout relay looks a little flaky as well. I'll have to do some research in my tech bulletins to see if there's a circuit diagram for a cutout relay equipped 3-brush system- - - -but I believe I have one that also includes the circuit for the output boost through the headlight switch.

The only way I'd spend a lot of time and effort on that system would be if I was doing a 100% original restoration. The 2-brush generator with the 3-unit regulator is a far better system, and not that expensive to convert.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!