For future reference, anytime you do serious IP work, ALWAYS apply vacuum to the shut off solenoid and watch to ENSURE that the stop lever moves. If it does not, DON'T START THE ENGINE. This means that the governor is not captive and the engine will run away.

Also, the easiest and quickest way to start one of these engines after dry is to hand pump, loosen all injector lines at the injectors about a half turn. Have an assistant crank the engine until you see fuel dribbling from one or more injector lines. Tell them to stop and tighten the lines from which fuel is dribbling. Repeat until fuel has dribbled from all and all have been closed. You were lucky this time, but follow the method and you can start one, even with a weak battery.

Hope this helps,