I would go with the Scarebird disk brake conversion brackets ($99.00) along with the Chev Celebrity calipers ($25.00) and Celebrity rotors for about another $25.00 all from eBay. Heck of a deal and its all brand new stuff and you don't have to change the spindles and upper control arms and mess around with 37 year old parts where the rotors are probably shot the the calpiers need complete rebuilding. I did a previous Kelsey Hayes conversion and it cost a lot of money (over $500.00) for ho-hum old brakes. I just did a Scarebird conversion and it works great. Check out their web site at:
http://www.scarebird.com/12802/21432.html