The little ground jumper on steering column handles horn and shift indicator lamp. I agree those other grounds at core support and firewall to block do need to be present.
Not necessarily. Our 65 has all the wiring correct but the grounding was bad at the horn. No honk-honk... Fix the ground and honk-honk.... All grounds matter. On a 60 year old car, the connectivity from front to back can suffer badly. best to check with a test light at all points.
