The best way is to put the whole set from halfcut if you can affort it.
the disc you bought have a same diameter and thickness with your rear brake set?
Ok guys I got plans to do up this old ride of mine actually can consider family car coz it's parked at the home most of the time as we got our rides. It's a Mitsubishi Lancer MX year 1997 1.5 DOHC triptonic no rust...