depending of which roundback alt you actually have, some have both provisions and you can get the unisolation kind brush and remove the isolated one oppositte to it ( attached an example of the alt with both provisions ), but IF NOT, simply replace the isolation washer on one of the brushes screws for a metallic one and will be done. No need for extra wires hanging around making that

for safety, cut the prong on it, to be safer from a wron brush field wiring