Eureka Jim,
You made mention of no ballast resistor. If a 12 volt coil was installed at the time of 6V to 12V conversion, it has an internal resistor. If it were me, I would get a new 12volt coil, get rid of the wire from the starter to coil, test the new ignition switch to make sure it is good, and simply run a wire from + on the coil, to the post on the switch that is hot when it is in the run position. Just my 2 cents, simple is better.
Jon
