Miscellaneous Ground Wires

Dana67Dart said
The dash housing is pot metal, the cir board is screwed to the pot metal, the pot metal is screwed to the metal dash frame, the metal dash frame is bolted to the car body, the car body is bolted to a cable that is attached to the negitave battery post.

View attachment 1715815923
You can always add an additional ground.

You failed to mention the ground jumper from firewall to back of engine block. That's how chassis ground reaches negative battery cable. Through the engine block. Later models got a 2nd ground jumper from core support to negative battery cable.