You could probably use the high and low wires as relay trigger wires. Run the power from the battery through a 20amp fuse to the lamps. All work done at front of the car near the lamps. I did a 69 Barracuda for a customer, but we replaced the intire harness with an EZ brand harness. And that was about 4 years ago so my memory has faded.
Brad


Check out the Dorn's 69 Barracuda "Switchblade" in the Nov.2010 MCG
Check out the Dorn's refurbished 36 Ford in the Feb.2011 Street Rodder