Have a 73 Roadrunner with 440 motor, now running a carb with electric choke, where exactly is the best place to tap off of for 12 volt hot wire for the electric choke

the blue ign1 wire running alongside the pass valve cover going to the alt field. You would want minimal voltage drops everywhere in that circuit.

And thats what factory did. On a 73 in fact, the provision already exist on harness, with a female packard terminal/plug floating around