I just examined my AAW engine bay wires installed in my 1965. One really large gauge red wire comes from the alternator and runs straight to the + battery lug on the starter.
A dark green wire runs straight to the horn. That means the horn relay must be part of the fuse box.
I don’t have any helpful answers yet. But I might if I pull out my AAW instructions. Have you tried calling AAW tech? They have great customer service.