I got to thinking about my suggestion for that connection I have a voltmeter in my aftermarket gauge cluster so I can get away with using the solenoid as a pickup point. But, if you are going to use the stock ammeter, then you need to use the generator side of the ammeter as the connection point.
There are no 12v sockets for the lights, I am still using the stock sockets in my 51, just put 12 bulbs in them. Generally, 1157 for the taillights and 1156 for the front turn signals. I don't remember any of the other bulb numbers though, a good parts store can get a 12v version of any 6v bulb. I did put new contacts in when I ran new wires.
Also, 12v circuits use half the current a 6v one would. So you do not need to upsize the wiring and 6v wiring is overkill for 12v, if you are going that way,