[thx569]

I've worked in bench electrical on starters, gens, alts, carbs, etc for a few years. It is possible to rewire a 6v to 12v. I don't know who or where you might get this done in your end of the planet. Call around to auto electric rebuild shops. Solenoid may not be the issue. Starter drive pinion may blow first.

I upgraded my 1950 Plymouth a long while back with good success. Used a resistor at the fuel gauge. Had to change lite bulb sockets front and rear. I didn't bother changing the instruments bulbs - just turned the dimmer rheostat to lowest setting, bulbs were still very bright. New 12v blower motor and generator/regulator. I left the starter alone at 6v. Spun the engine over very easily (and fast). Blew the started drive after a few years. Carried a spare 6v starter in the trunk just in case.