Re: xy brakes
I did this conversion on my XY a few years ago.
Parts needed are:
Both front wheel spindles and callipers and flexiable hoses.
Brake booster and master cylinder for disc brakes, plus mounting bracket for booster.
The 3 brake lines for disc brake master cylinder. (Drum brake lines can be made to stretch, but it is easier to fit the disc brake lines).
Disc brake peddle.
I got all the parts off donar cars. XB callipers and spindles. XY booster/master cylinder/bracket, brake peddle and lines.
It took me a afternoon with not to many problems.
I hope this helps.