I'm not sure what ohm level ballast resistor that Ford used - probably somewhere around 1.5 ohms but not sure. I think it's about as much art as science in selecting the resistor. I know old Corvettes started out using one around .8 ohms (from memory) and then to reduce incidents of burned points, went to a 1.5 or 1.7 ohm one (don't hold me to exact ohms).
If no one can answer your question I can give you the name of a Ford distributor rebuilder who should be able to tell you.
Tim O'Connor Distributor Rebuilding and Restoration - Home (
Tim O'Connor Distributor Rebuilding and Restoration - Home)