I'll take a stab at it since if I'm wrong someone will point it out. I'm looking at a chassis service manual for a 67 Camaro. The 67 RS had electric headlight doors, but there is no mention of it in the book or your email, so chances are it does not matter anyway. The Electrical diagram of the horn relay shows a red 10 gauge wire coming indirectly from the positive terminal of the battery. It also shows a 16 gauge brown wire from the horn relay to the fuse panel. The brown wire has a disconnect in it. If you are trying to put the circuit breaker on the 10 gauge red wire, obviously the battery side goes toward the battery. If it is on the brown wire, the battery side should lead to the horn relay.