On the original set-up, there is a black ground wire connected to the inner brush. But, it isn't providing the ground for the brush, it's mounting screws do. Instead, it's picking up a ground and carrying it to the regulator. So, maybe try connecting your reg/rec black ground wire to the inner brush?
Brown or green wires don't connect to the inner brush, or to each other. Brown is switched power from the key and was originally fed into the regulator. Green is regulated power coming out of the regulator and running to the outer brush.
Have we established that you have the correct reg/rec for a '79 and older alternator? One that sends a regulated power signal to the outer brush? Is yours just like the one in the link you provided to that other thread? It should have 2 plugs on it so it can be connected up like the original components were (plug right into the stock harness and connectors).