I would be sure to talk to Ron Paige Metcalf, RPM Co, about Cad Disc Brake Conversions.
This man spent a Career Restoring 41 Cads, then slowed down, to manufacture Disc Brake kits for Later Cads. I bought a kit with Double Diaphragm Master Brake Setup for My 60 Cad, just finishing the Bolt-in System. No fabrication Req'd, all was furnished by Ron.
I believe the Discs and Calipers on Mine are 68 Cad. The Power Master Brake Cyl /Diaphragm is Corvette.
RPM Phone is 1-877-329-1885. You will need to leave a message.
He is in Hemmings under Power Steering Systems
Good Luck, Pete