Brake Lines...

Hello there. I have a 1970 dodge dart. It is a four door and has drums on all four corners. She is in need of brake lines bad. I was told when I bought the car the brake lines have already been replaced years ago. I just had a question about the size of brake line I should use. I want to go back to factory specs. The current size of line on the car is 1/4 inch. Does anybody know the factory specs??