rearend swap

i thank i've got everything for my swap finally i'm swapping my 7 1/4 for a 81/4 mines 71dart the 81/4 sfrom a 73 dart the perches mesure the same but backplate to backplate the 71/4's 50 an a 1/4 inches the 81/4's 48 and a 1/4 i've bought a set of ralleys for the 81/4 to match my front anyway it looks like my tires might rub the leafs i don't won't tobuy offset rims anybody know if this will work or give me any info.i have started yet was pbbblasted bolts today and measureing where can i get abody rearend widthes somebody might have changed it before it had pizzacutter tires on it hope thats not why