If your 6V starter is in good working condition there is no need to have it converted to 12V just for the sake of having a 12V starter. Mine needed to be rebuilt anyway and I asked if he could convert it and he said yes so I had him do it.

"It's just a phase. He'll grow out of it." Mama, 1964

1956 Chevy 1/2-ton 3100
1953 Chevy 6100 "The Yard dog"
1954 GMC Suburban Now with a new proud owner.