I would just buy a 6 volt NAPA Echlin coil.
It won't just bolt on like factory though.
His ignition wires and or distributor had issues.
My parts trucks will always start reliably even in the wettest weather.
The twin carbs though will run dry after sitting and require cranking a bit with the choke on to fill the carbs.
Just carefully go through the ignition system....not much there to do.
Install good quality american made points and condenser....no china modern ignition parts...coil will be though if new. Keep your old coil just in case..