The wire that goes to the ign switch is what I term "a big red wire". On the inside of the car, it goes to the bulkhead connector and a similar "big red wire" exists on the underhood section of the bulkhead connector.
Reason I know this is that a prior owner of my '67 Newport had used that ign switch power wire to power "something", so he just removed the insulation and scabbed the new item to that then-bare wire, covering the "splice" with chewing gum paper. One night, the car died. Everything inside the car did dnot work, but things outside of the passenger compartment did work. Got it towed to the house, a few blocks away. Diagnosis found the splice! I got factory-style crimp-on terminals and insulators, a piece of new red wire, and plugged it all back together. Fixed . . . except that sometimes the connector at the bulkhead connector can slip off, so have to plug-in that "big red wire" terminal there. Need to "tighten it up a bit".
If you do not already have one,
www.mymopar.com (might need to manually input that address) for a free download of a similar year and model Chrysler factory service manual. Free.
Just some thoughts and experiences,
CBODY67