Such occurrences are a real concern for the antique vehicle community. A 64 year old truck has been exposed to all sorts of weather conditions and of course critters that like to chew on wiring. Heat deteriorates wiring insulation and just moving the wire to get to something else can cause the insulation to fall off. Could you have done something to prevent this from happening? Probably not given where the short was located. Count yourself lucky that it happened while you were there instead of in the dead of night when you were awakened by the fire truck sirens. As you have figured out, a new wiring harness is in order. You got this!
