14 GA or 16 GA Fusible Link?

I honked the horn with the motor off and the ammeter did not budge. It shows a charge with engine running.

What is good on the '65 design, is that the ammeter wires don't use the main harness plug coming from the engine compartment, they have their own unique metal clamps with screws where they pass through the firewall all on their own.
That's correct for '65.