Reverse a 12v to a 6v possible?

[jchochole]

Hi Gents,
My new Model A is 12v and the previous owner is lying down permanently, so I can't talk to him. His conversion to 12v is incomplete and no lights were changed, all I have is a 12v alternator. If I go back to 6V Positive ground, and replace my alternator to 6V pos ground, then I think all I need to do is take off this voltage converter.

Am I on the right track here?

Thanks,
Jim