E Body 8.75 in a 67 Dart

Yeah, I'm sorting out what to do about perches now. When the swapped the F body rear they took the springs from the car with it, so I have the rubber isolater boxes and giant locater hole perches. Trying to figure out if I want to just buy new perches or modify the ones on it to fit or just buy new springs. Is there any difference in the backing plates between body styles? I had heard you could use the 8.25 plates if you drilled a fifth hole which was what I was planning to do. So I would keep all the brake setup I have and just transfer it over to the new housing.