The 6v starter should do just fine if it's in good condition. Here's a link to an article where the guy did a whole rewire on a Plymouth.http://www.rodandcustommagazine.com/...5_0310_rewire/ If you don't need to rewire, there's still some good pointers in there. I've used the "Runtz" resistor before, works great. See www.speedwaymotors.com