Yes Adam, yours appears to be a "type A" charging system. That means the brown wire (the top one in your pic) to the inner brush should be hot (12v) from the key. The green wire (outside brush) is a regulated ground from the regulator. My video on testing the reg/rec only tests the rectifier (rec) side of the reg/rec, so there's no need to do that at this time. Your problem is with the regulator side of things. So here's how I'd proceed....I will try tomorrow Jim's suggestion to test the Reg/Rec as shown in his video. I guess the rotor /stator gets energized via the brushes with Ignition on?
1. look at the brushes and verify the length. Don't recall what it's supposed to be, but there's a line molded into the brushes at the minimum length mark. Just make sure they're longer than that. Give us some pics if you're not sure. If they're good, proceed to step 2. If not, put some good brushes in there and see if you get magnetism.
2. Use your meter and see if you have 12v at the brown (wire) brush with the key turned on. If you do, proceed to step 3. If you don't, we need to figure out where you're losing it.
3. Disconnect the reg/rec and turn the key on. Take a jumper wire (or pliers... anything metal) and touch it to the green (wire) brush and put it to ground. Provided you have power at the brown brush, grounding the other (green) should energize the rotor. If it does, you'll feel the magnetism on the nut holding the rotor on.
Let us know what you get and we'll proceed accordingly.