Here is a basic drawing of a 12si schematic. There needs to be a heavy gauge wire (12R) direct from terminal B on the alternator to battery. I'm not personally familiar with the 63 but on my 66 this is similar to how I rewired mine. Not sure I follow your description but it doesn't seem like you have anything directly sending current to the battery. I have a 12ga wire going from Alt to my horn relay (junction), and from the horn relay to the battery.
