Rear Brake Up Grade

I Have 98 Toyota 4runner Limited. And Was Wondering Bout The Rear Brakes Do They Make An Up Grade? I Want To Put Disc On The Back And Didn't Know If The Lexus Rx300 Rear Brakes Would Work Cause I Have Crossed Drilled In Front And Ugly Drums In Rear It Would Be So Bad If I Did'nt Have 23's On It. Any Advise Would Help Thanks David