Just another thought while Im on the truck starter issue, 6 and 12 volt etc. It is possible to take a mid to late model 1950s 12 volt 4 field starter and modify it to work on the 1940s 216 motor without changing flywheel etc. It would give you an actual 12 volt direct replacement that would bolt up without changing flywheels. Also, Im pretty sure I can take a 55-61 6 cyl Chevy truck starter with Hydromatic Trans. and modify it to replace the 216 starter, giving you a 12 volt 4 field replacement with elect. solenoid on it so a key switch could be used and again, no changing of the flywheel. Interesting what you can do with old Delco starter...LOL.
Ken