If you have no pedal it could also be the result of a poor install.
The brake pedal linkage differs between the 1964 single reservoir master cylinders, and the 1969-'72 brake parts (made in Pakistan, India, or the bad part of Asia) that most vendors source for their brake kits.
If the person that previously installed the brake kit bought his kit based upon price then he gets cheap oversea car parts and they do not provide the proper conversion parts to complete the install such as multiple adjustable piston rods to match the brake pedal to the master cylinder.
Try and use stock parts and the rod might not reach the bottom of the dual master cylinder bore, resulting a spongy pedal with a lot of effort. There are also two holes punched in the hardened steel brake pedal to account for the added stroke of the power assist brakes. If they used the same manual brake hole that could also be an issue. The power assist booster bolts to the fire wall at a different angle to compensate for the change in the angle between the two holes. Pick the wrong hole and the push rod will bind on the master cylinder bore.
There are allot of factors beside price that are involved in adding disc brakes to an older car.