Your 67 7.25 should have 9" brakes, and none of those parts,AFAIK, will transfer over to the 8.75. If you install the 10" stuff onto the back, and still have the 9" drums up front, You may have a brake-proportioning problem . If the rear brakes work too well, and if they lock up, then you could find yourself in a spin; that is to say the rear could slide to the side and try to pass you.. I say could, cuz it depends on some factors such as; rear tire bias,thrust angle,driver reaction time, and not much else,lol.Once the rear is sliding, you may have only milliseconds to avert the spin.
For a streeter,10" drum brakes on the back are more than adequate even with discs up front.
