The 63 does not have self adjusting brakes. IF you add disc to a 63 you still have to adjust the rear brakes. You could retro fit the rears for self adjusting brakes. It may be a non issue if you decide to change the rear axle for better gear ratio.
The 64-66 are self adjusting, and adding disc to the front, doesn't change anything as far as brake adjustment goes.
Larry
