Battery disconnect will not kill the engine. It will only disconnect battery power. With that said, disconnects are most times only in the ground cable.
Do wha...? If your pump shutoff is manually operated it wont matter what you do to the electrical system it's still gonna run. Air shutoff and be done...
If you want to stop the engine simply cut power to the fuel solenoid. Since you started this thread in the sled pulling section we can only assume you're asking about an emergence kill/shut off in which case the only effective means is an air shut off on the intake.