1. Starter has nothing to do with charging. The starter just turns the motor for starting and, in case of a 12V system, provides a "bypass" during start. To save points.
2. I assume you are keeping the 12V system. I.E. coil, battery, bulbs, Ballast resistor, etc....and points distributor.
3. The old 6V starter will work with the 12V system.

You will need to change the button on top of the starter to a "side terminal" type. The solenoid has a "R" terminal for bypass and the foot style uses the side terminal button. Click

The ballast resistor is used for a 12V conversion. It is used with a 12V coil that is externally resisted. If you have an internally resisted 12V coil, you don't need a ballast resistor or side terminal button. If you have any questions feel free to ask before installing anything. Also, I'll try to send you a PM (Private Message). I don't know if you can receive them as you are new. Guess not. Maybe moderator can advise.

Nice to see a fellow from Down Under. Greetings from Up Top.

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn