Dead

I tend to prefer pictures and drawings, but everyone is different, so if this is helpful great. But if it doesn't make sense, please say so.

The main circuit has two power sources, alternator and battery.
All power is distributed from the main splice (except for the starter & starter relay).
On your '64, there should be a fusible link somewhere between the junction on the starter relay and the bulkhead connector.
Here's one on a '65.
upload_2020-1-18_14-35-12.png

and the original off of my '67
upload_2020-1-18_14-38-1.png

When that melts, everything will be dead.
upload_2020-1-18_14-42-41.png

If the headlights or parking lights work, then there is power to the main splice.
The ammeter will show moderate battery discharge when they are turned on.
It should show small discharge with the key in run or start.

Post back what you find.