10 X 1.75 rear drums on 7.25 rear vs. 8 3/4

Yes I just parted out a 74 dart swinger with a 318 and it had a 7 1/4 Big bolt pattern with the larger 10" brakes . I installed it for now till I get my 8 1/4 built with a suregrip and different gears ? Used the 74 7 1/4 instead of the 69 because I swapped the front disc also with the larger bolt pattern. I wanted the front and rear to match . I had to buy new rims and tires . What a tragedy!