You'll need the starter switch for a 12V foot start engine. It's a direct swap for the 6V switch, but it has a small side terminal built in to provide the bypass voltage to the coil during starting. Rock Auto stocks them but they call it a "starter solenoid", not a "switch".
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!