I’d venture to guess that it is a 50012 that somebody has added a starter to. That’s ok, especially since you have a wiring diagram and enough knowledge to figure it out. The starter solenoid primary ground is completed by the safety switch when throttle is set at a slower speed. Firing order is 1-2-3-4, #1 being nearest the top, #2 next one down, opposite bank, #3 next down, first bank, etc
