There is none
There is only one switched ignition lead into the engine "room" and that is IGN1 usually dark blue. It powers the ballast resistor, depending on year, the VR, the alternator field, and electric choke, and smog doo dads if equipped. THIS GOES DEAD during cranking
The ignition bypass, IGN2, usually brown, connects to the coil+ side of the ballast. This comes direct from the ign switch AND IS ONLY ACTIVE during cranking. It is SEPARATE from the yellow "crank" wire that triggers the start relay.
What you must do is either change to an ignition system that DOES NOT use a ballast resistor, or else go through "other shenanigans"
With an ignition system that does not use a ballast, jumper the ballast resistor terminals together and use the old coil+ wire for your feed, "basic."
But BETTER is to use that wire to trigger a relay, and feed all underhood loads off the relay. This is because of common "harness voltage drop" which lowers voltage to the VR and causes over-voltage
Electrically cut the blue "ignition run" wire coming out of the engine bay bulkhead and wire the bulkhead end to trigger a relay. Connect the engine bay end of the cut wire to the load output of the relay. Power the relay contact off the starter relay through a big fuse/ breaker.
But since you are going to jumper the IGN1 and IGN2, you want to add IGN2 to the relay trigger.
Find and download a shop manual and wiring diagrams, from MyMopar, free
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If for some reason you are going to retain an ignition which uses a ballast, now you must "do shenanigans." Since the IGN1 goes dead in start, but is alive in "run" you MUST tap into that for your EFI. In order to get voltage during cranking, you need to "add" the IGN2 WITHOUT causing a feedback/ interaction between the two. There are a few ways to do that.
One is to add a relay in parallel with the starter relay, that is, wire the coil of the new relay to the coil of the start relay, so the two fire up together. Power that relay'z contact, and run the load output over to your IGN1 going to the EFI.
Yet another way is to tap off either the IGN2 or START wire and use a big diode to isolate. maybe a 5A 50V rectifier diode. Hook the end of the diode with the bar designator to the IGN1 tap and connect the remaining end to the START wire or to the IGN2 feed.
