I have a 54 chevy Bel Air in my "collection". It has the 6V key operated starter with the solenoid mounted on the starter field case. So, if I get a 12V solenoid this might work? Any idea on the possible part number? I would be okay with leaving the rest of the starter at 6V for now.
It might also be possible to wire a heavy resistor in series with the solenoid winding to prevent damage to the pull-in winding. Here is a selection of ceramic resistors on Ebay. I'd recommend the 10 ohm 200watt.
www.ebay.com/itm/225854220831?Jerry