71 Dart Brake Conversion Kit???
I recently did that swap on my 69 barracuda. Unbolt the 2 bolts from the inside of the upper control arm, separate the lower ball joint from the lower control arm, disconnect the rubber brake hose where it connects to the steel one. You need all of the parts that are now loose. (do not need the lower control arm unless it has sway bar mounts that you want), I did not have power brakes on mine and also got the power booster, master cyl, and proportioning valve (prop valve is different between disk and drum brakes). here is a link to a pretty thorough writeup.
http://www.moparaction.com/Tech/archive/disc-main.html