6V passenger car starters had a solenoid engagement from about 1951 on. Also cabover and step van trucks. You might need to install a 12V solenoid to avoid burning out the solenoid pull-in winding pretty quickly. There's a 12V solenoid for a mid-1950s Olds or Buick starter that can be adapted to the Chevy 6V solenoid starter.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!