Yes, Everything.
Remove the booster, distribution block and proportioning valve, disc brake pedal and switch.
The disc brake spindles, distribution block with proportioning valve, and brake calipers are virtually the same 1968-69.
You can modify your drum brake pedal hanger for use with disc brakes. You must knock off 3 of the captured nuts that face the fire wall. Only one of them is used with disc brakes, it should already have the hole drilled for the longer disc brake pedal. 1969 disc brake pedals work fine in 1968's.
Booster Dewey in Portland, Oregon, is hard to beat for rebuilding the booster.
Compare the hole on the 1969 when the booster comes out, you will need to enlarge the hole and or remove some metal on the firewall.