Same deal w/ my 1965 383 decades ago. I had just come back to the U.S. w/ a small son and temp living in a motel where I knew few people and wife still overseas. With battery getting low and feeling desperate (how to get to work?), I decided to try new plugs. Saw a faint coating of black carbon on the white ceramic. I tested one and saw it wasn't sparking at the tip, but rather conducting thru the carbon. It had been too-rich initially and I didn't know that alone could disable you (never liked that Rochester WWC 2 bbl carburetor). With new plugs, it fired right up. Switched to my 69 Dart slant six from the storage yard since though it like to idle rough (lean Holley 1920), it always started.