Rotors
You know what, you might get lucky. There were 3 different disc brake systems used in 68. Bendix, Budd, and Kelsey-Hayes. Flip the assembly over and check to see if your rotors are just bolted from the rear. If so the studs will be ok. Show us a picture.
The actual procedures are in your Factory Service Manual in the Brake section.
If you don't have one, free downloads are available.
