4" to 4.5" rear wheel bolt conversion on a '64 Valiant?

Can anyone suggest the easiest way to install 4.5" bolt pattern lugs (drums) onto an existing '64 Valiant? Or is there another Mopar compatible rear end that will bolt in? Converting to disc brakes on front with 4.5" lug pattern for greater choice in wheels. Thanks!
This was my first post and I've just got to say Thanks to each of you! It may sound strange but just getting an answer to a simple problem so quickly, and by guys who've "been there-done that", sure blessed my heart! It's like I was asking an ole' uncle or something! :)