7 1/4 to 8 3/4 swap in A-body

Actually I think it's more like 2 1/4 inches it will need to be shortened.

As for the shock plates if your car is a 73 to 76 the axle tubes will already be the 3 inch size so you won't need to change the plates, the brakes will bolt on too but, you'll need the big bolt pattern axles.