The reason that I asked the question about speed was because I had a 1966 Newport without power brakes which I would say stopped very well at low speeds (super sensitive) but which stopped very poorly at high speeds. At lower speeds it was difficult not to do a "hard" stop and on the Freeway hitting the brakes often only resulted in the vehicle changing directions. This continued after I had replaced everything in the braking system (metal lines, rubber lines, master cylinder, wheel cylinders, shoes and turned drums). I would guess that if this car had power brakes it would have been difficult to drive at slow speeds, but much better at high speeds.
My solution was to put front discs off a 1972 Fury into it. This was interseting without the power boost because the pedal effort was pretty high. However, you had good brakes that you could hit at any speed without holding the steering wheel and the car would still go straight.
