Oh yes, been there, done that with our 75 Mav race car. First, the problem seems to be with the carb hook up(Holley or Edelbrock on a after market intake). When mashed to the floor, the pedal has to much clearance from the arm to the floor board and the linkage on the carb is wide open against the carb. As you are trying to get more power out of her, the cable is being stretched against carb link. If you try to move the spring end foward on the linkage it solves that problem but then the throttle plates will not open fully, solution we came up with was to put a pedal stop on the floor, under it, at wide open position(1/2 bolt and double nut through floor). Other fabricated stops can be used too. We have not broken a cable since. Because of scarcity of V8 cables, we use 6cyl cable assy. from Mav's or Fairmont's just need to put a little loop in it. I think Granada will also work. Just have to match up depending on years and engine. Could go to after market racing type, but they cost a lot more. Hope this helps