Car won't start. Could miss Carlisle! Please help.

Yes on the electric choke. Is there a better place for the choke?
Was a good guess huh? I suppose you do want it switched and that is the switched hot. That factory wire is plenty sufficient for signaling a relay and a relay would supply everything through added wires and fuses. The very best way to power a electric choke is through a rear defrost timer module robbed from a later model whatever but that gets complicated. Adding relays, not so much. Good luck with it.