Where can I hook up an electric choke?

I think you could use the positive at the coil


No, the coil only gets 6 volts, the choke needs 12 volts...


Hook it up to the input side of the ballast resistor with a piggyback terminal.

disconnect both connections to the ballast, then turn the ignition on, then poke each connector with a test light and see which one is hot. Use that one to feed the + for the coil...