9in rear drum rakes; do 7 1/4 and 8 3/4 interchange???

Well while doing my suspension up grade tonight I noticed my 8 3/4 on my early dart as the big 10in brakes while I have the 9in up front. I know not good. Can any one tell me if the backing plates and all off of a 7 1/4 will fit an 8 3/4?? That would be nice then I could just swap them out. Other wise I will be looking for a set of 9in 8 3/4 brakes! Thanks!!!!!!