Bobs link shows you all the pieces you will need to change, and then keep an eye on ebay.
I picked up a complete disc set up for a 67 mustang i'm building for my sister&brother in law off ebay for $110 that included the spindles,calipers and basicly everything to swap to disc with the exception of the rotors. Usually you can find those parts on ebay all the time for a good price.

BG