ClassicCar

Assuming you are going to keep this car, you might want to join a club dedicated to this make. They would have resources for parts and historic / technical information. As far as I can see, that would be the Chrysler Products Club:

http://www.chryslerclub.org/links.htm

As to the 12 volt changeover, I would caution against it, at least until someone can present you with an itemized list of exactly what to do, and what parts to buy. When these cars were new, they worked quite well on 6 volts, year round. Due to the effects of age, wiring and electrical components wear, and 6 volt systems are not as forgiving of wear as 12 volt systems are. You will need to make sure everything is in tip-top shape, especially the connections. But then, all old cars require a bit more maintenance than today's cars, so you had better get used to it! I went out last week and started up my 75-year old car (which sits in an unheated trailer) after it had sat for a month or so. Six volts. No problem. Be sure you have a GOOD battery with plenty of cold cranking amps (mine has about 780) and be sure the battery cables are the correct size for six volts (WAY thicker than cables for 12 volt). And like Russell just said, make sure all the battery connections are "bright and tight". Clean batt. terminals and cable connectors with the device you can buy at the auto store. Converting to 12 (or even volts is what people do as a band-aid to some deeper problem with their engines. Treats the symptom, not the cause.