Normally on most later model years, from 1962 and up to 1973 Mopar's the big red wire from the alternator is routed to the starter relay and then down to the big positive lead from the battery on the starter solenoid, this routs the current made by the alternator to the battery.
What you need to do is to make sure the car will not run with the battery cut off switch turned off, by routing the feed to the battery from the alternator back to the cutoff switch you are isolating the current to the rest of the car when it is turned off You are creating a switch that isolates the alternator feed from the rest of the car when turned off