I am thinking about converting to fron disk brakes. I have some questions as to what I need. Do I need a new booter/mastercylinder? See pic
http://www.adlines.com/sprint/booster-master.jpg

is this where the proportioning valve would go?
http://www.adlines.com/sprint/brakevalve.jpg

the last thing is will disk brakes cause a problem with my 15x7 crager SS mags?

You will need new spindles,rotors calipers, master cylinder, brake booster, combination valve and the front brake lines, also you may have to change the stroke on the brake pedal. If you are swapping from a power car to non power car of the same model the upper control arms should be the same. If upgrading to 11" or 12" you will need adjustable upper control arms. Do a search there is much info on this sight.