If you want an original looking harness I can also recommend YNZ. I bought the harness for my '38 from them. The cloth covered harnesses are expensive. Why convert to 12v? If you're just wanting to push a radio you can buy a step-up to power it unless you want a door thumper.
No door thumper needed. Just trying for consistency. I have converted my Allis Chalmers G tractors to 12v as I did with my Farmall Cub. This way everything on "Hell's Half Acre" is consistent. My other tractors (Olivers) were already 12v.
