Sounds to me like this is a simple matter of cylinder bore size. As others have said, I bet you'll need to add a prop valve.
To give you an example (I don't know what my car "is" for master size) I'm using 73/ 74 Duster/ Demon in front on my 67, and a disk brake factory 9" Ford out of a Versailles, so 4 wheel disk brakes. I "tried" t he factory master and it works just great. But we are talking 2 more disks and I don't know how the bore size compares to the newer cars.
