1966 charge indicator light

i have a 66 GT350 with stock wiring and alternator. As the amp meter is not the most accurate thing ever made i want to fit a charge indicator light as a safety measure. on a 65 the light is wired between the ballast resistor and terminal 904 on the regulator. on a 66 getting to the resistor wire is not a problem but terminal 904 is wired to the accessory terminal on the ignition switch. someone must have done this

thanks

Skunk 95