Welcome to the "Achilles Heal" of the 1967 through 1969 Imperials - the front disk brake system. Both rotor and calipers are a problem (reliability and availability). My solution was using Camaro (yes Chevy Camaro) rotors and 1970/73 Imperial calipers (both items readily available). I must admit I am guilty in not doing what I promised last fall and documenting this conversion fully (including a complete parts list) for the Imperial web site along with detailing any issues I may have encountered. The main reason is that I still have not completed my 2000 miles of road testing along with a final tear down and inspection that were my prerequisites in my finalizing the documentation of this project (also we bought a new (used) house and I have been doing many "honey do" projects).
PS 1) My brakes are working great. 2) I had a ball being the "pace car" (at 3 mph) for the Prospect City July 4th parade. I really bought the car to drive the beauty queens in the parades but in this case I got stuck with the mayor.
Don Dickinson
Prospect, KY
1955 Imperial Newport, Canyon Tan and Desert Sand
1967 Imperial Custom Convertible, Ivory and Burgundy