Conversion to !2 Volt system

I have successfully converted my 1955 Dodge Custom Royal to a 12 volt system except for the Windshield Wipers. I have been told that the switch and wiper motor must be replace or rebuilt to a 12 volt from 6 volt. My question is -Can a step down transformer (12 to 6 volt) or a resistor be used instead of replacing the switch and wiper motor.
Author: ole55dodge