Where to mount the circuit breaker? IMHO, as close to the power source as you can so it protects as much of the wiring as possible.
I have no clue what the door wire shields would look like for a '54 Vicky, but if they're anything like the 55/57 T-Bird ones, these might work.
http://www.parts123.com/parts123/yb....Z5Z5Z50000219a
http://www.parts123.com/parts123/yb....Z5Z5Z50000219a