Headlight Switch

From what I have read here sounds like you dont have clear understanding of how the electrical system works. That said you would be better off buying a new switch and not try putting in a toggle. the conversations I read are confusing a breaker with a relay. the original switch does the dash lights, parking lights, dome light, and head lights. if you are doing an all new wiring system for the car it will take a couple of toggle switches to replace the original and several relays so you can use smaller wire to the switch and larger where you actually need it.
I recently refurbished my 74 dart sport dash and needed a new switch and got one off ebay for about $20 be careful there are several different switches and shop around the prices were all over the place for the same switch. I also liked the effect of LEDs in my dash
Mike m