Not really- - - -it would require a much higher resistance than even the regular ballast resistor provides. "12 volt" coils actually operate at approximately 9 volts so they can work efficiently during cold-engine cranking when the terminal voltage drops. A bypass circuit is provided during cranking to eliminate the resistor. Once the engine is running, the resistor goes back into the circuit to protect the points from overcurrent burning, something that will happen very quickly if you try to use the 6V coil on 12 volts.

Use the correct coil, and add a resistor and a starting bypass circuit like the later-model trucks had. If you've got a stomp-type starter, a switch from a 12 volt starter can be installed on the 6V starter. It has the bypass terminal necessary for correct 12V ignition wiring.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
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