slant 6 ignition problem !!

I would be tempted to pull gage cluster for easy access to all wires passing over steering column, attaching to gages, headlight switch, and fuse block. This is where 80% of the melting will occur. The other big cluster is at wiper and ignition switch.

If I had to guess, whatever shorted out caused the fusible link between battery and bulkhead connector to do its job; open the main circuit supplying dash area.

Something melted, and you have to locate and repair it before reconnecting the battery, or the fire gods won’t give you a second chance.