Electrical/starting problems

Does that mean your problem is fixed? The bulkhead Z connects to Red wire of ammeter, that should have power. Last I knew it did not, so that can only be connector issue at Z. Have you pulled the connector to check? They are Packard 56 series quick connects, and are troublesome after 50 years.
The problem hasn't been solved. The connection from the starter relay post, through the fusible link, through the bulkhead connection Z and to the ammeter red wire was checked and is good. Before I started this post I completely disassembled the connectors on the engine side from the bulk head connector and looked at each connection and cleaned up the Packard 56 connectors. I used Deoxit on both the male and female connectors before I reassembled the bulkhead connector.