I can’t read proposals, hooked to a question (how cheaper?) without shuddering in disbelief.
Probably the cheapest way to convert any 6 volt car to 12 volts, and keep it the same 1952 Plymouth you yearned to own, is DON’T convert it.
Antique and classic cars are valued because of their appeal as a link to a time passed, the connection to the time and technology in play when they were constructed, and, if that don’t ring your bell, try using them as a material link and stimulation to research history.
I have three cars, and a tractor, which were built with a 6 volt system, and all except one (the 1923 DB Roadster is factory 12 volt) very happily coexist with 6 volt electrical systems. And, as their adopted parent and caregiver, I am super satisfied with the performance they have provided me in the past 4 years, and their previous owners over a period of 70 to 94 years.
I have a daily driver, I have a classic, but very dependable pick up, and I have my HOBBY cars. I drive my daily driver because it has power steering, brakes, seats, a back up camera, heated/cooled seats, satellite radio, lane change warnings, and a thousand computers to go bad and justify paying for their very expensive replacement.
My 1995 Ford F-250 is neither a sex symbol, a chick magnet, or will win a lot of ooooh’s and aaaaaaaaaah’s from pleased and agreeable onlookers. But, although it doesn’t have any power seats, windows or four wheel drive, it will pull my equipment trailer, carrying my 1947 Ford 8N tractor and 1941 Massey Ferguson brush hog, at 60 MPH, for a distance as far as I wish to travel.
On the other hand, the uniqueness of my 1927 Willys Knight, my 1951 Plymouth Cambridge, my 1929 Fargo Express Panel and my 1947 Ford tractor is that they are representative of vehicles made in 1927, 1951, 1929 and 1947……..and it is beyond me as to why I would spend one hard earned cent to change that.
Oh, my KIA Sportage, (aka daily driver) also has a satellite radio, LED lights and a solid state anti theft system……and I own the KIA for that reason, and because it is my daily driver, and depends on a 12 volt system, would never bastardize it by converting it to 6 volts. Nor will I ever bastardize my antique vehicles by trying to convert them to replace my daily driver.