OK, this topic is moving into a new area that also has the potential to get a variety of opinions.

12v generators can be easily found and a bracket should be easy to find with a used generator. You should also get a matching voltage regulator.

If you want the simplest, most reliable, and best-performance (non 6-volt) charging system (at all RPM), consider an alternator. The simplest alternator to install would be a one-wire alternator. You will need mounting bracket(s) and if you want to buy it/them (this bracket set might work on your 216).

You may use your existing generator wiring. Maybe someone with first-hand experience will post information about how to hook this up to you ammeter/voltmeter (what was used-in or is available for a 1946 truck).