The 1965 Mustang
had drum brakes. If you are trying to restore your car, one often overlooked source of parts is the 1964 -1966 Ford Falcons! They had the same drive train, suspension, and even the same dash!
Brake lines are easy to replace, using lines that are available from any parts store, and bending, cutting and flaring to size! If memory serves me correctly, and you want to upgrade to disk brakes, you can use parts from the late 70's Granada!