I apologize for being harsh, But yes it is always best to start a new thread so we don’t go running off on some blind alley. But if it helps the two motors in question have different ignition systems. As for stator interchangeability, I’d have to put some research into that.
Anyway, starting is totally dependent on the battery. So a bigger alternator isn’t going to help with that. You are bridging some sort of high resistance with that jumper. Find the resistance and fix that.