On upgrading to at least 12" rotors, the factory large bolt pattern has two setups, including the 11.75" police package rotor setup. Thats the least expensive route. On the moparts message board there is a regular there that makes available a caliper mounting bracket that can mount Viper calipers or the Wilwoods. The member's name is Andy F, I think his name is Andy Finkbeiner. I will check.
I have driven the 11.75" factory setup on a 1970 340 Dart Swinger; the setup stops on a dime and returns 9 cents! Highly recommended for an A body!
Check out Andy's website!
http://arengineering.com/
Here is the link to the caliper mounting options:
http://arengineering.com/caliper_menu/calipermenu.html
