12v '38 Ford - confirm polarizing method

[46wischris]

Finally got new tires mounted on the '38 we bought earlier this year. I've only started it a few times, wasn't going to take it out before replacing the 50 year old tires. I just noticed that the amp gauge shows discharge when revving the engine. The seller had installed a new battery, so I assume I need to polarize the system.

Background - a few years back the '38 was converted to 12v negative ground with all new wiring. From L to R, VR reads Gen, Field and Batt. The VR has just one wire going to it, at the Field terminal. Researching the topic of polarizing, I've gotten confused. Am I supposed to 1) remove the Field wire and touch it to the Bat terminal, or 2) touch Gen and Batt terminals, or 3) leave Field connected and touch Field and Bat terminals together?

I also noticed that the negative battery cable grounding to the block is much heavier gauge than the positive cable going to the solenoid. Is that OK?