John........would it surprize you to learn the starter motor don't care, positive (+) or negative (-) ground, it ALWAYS turns the correct direction to start yer engine. And yes, you can run yer 6-volt starter motor on 12-volts.
Would it surprize you to learn yer 1-terminal squarecan frontmount coil don't really care positive (+) or negative (-) ground either??? While it came 6-volt positive (+) ground from the factory, many neubie shadetree mechanics install it negative (-) ground just like their 12V-V8's. It will start and run just fine. .......Dell, yer self-appointed sparkie-meister