Disc brake conversion on a 64?
This one is easy. Sorta...
Find a '66 T-Bird in the boneyard. A '66-'69 Lincoln Continental might work, too -- they had similar cowls, front suspensions, etc.
Unbolt everything that has to do with the brakes. Bolt it to your car. Presto!
I'm sure the '66 T-bird had K-H discs standard. They were 11.875" diameter, about an inch and a quarter thick if memory serves, which is big-ass in any book. They were used to good effect in TransAm racing Mustangs and NASCAR Road Racers.
They are the 4-piston style, and getting a little harder to find parts for these days, relative to the later single piston calipers used a few years after... they tend to jam pistons, and are susceptible to corrosion.
Not sure about big car knuckles, bearings, etc... the chassis was different than the Galaxie, I know that . The T-Bird was a unibody, the Galaxie, body-on-frame.
You might want to look over at the Lincoln Continental Owner's Club boards, they are very active tinker-ers with their cars, and would know if and how the parts might interchange.