Brake Lines

I have a 72 Duster that had front drums and /6. I upgraded to disc brakes and now have the K-frame, front suspension, and front brakes from a 74 Dart. I need a new set of front brake lines and I don't know if I should order based off 72 or 74...? Does anyone know what the difference is between the 68-72 and 73-76 brake lines?
Thanks!