rear disc from grand cherokee on a 8 3/4

Hi. My brother is doing the same conversion on his Duster right now, 1973 8-1/4 rear. He didn't have to drill any holes just grind the hole in the bracket a little larger as you did. It's almost a direct bolt on. He is also trying to figure out parking brake cables, nothing yet. I'll let you know if he comes up with something. Bobby