The disk upgrade can be done with OE parts from the JY and auto parts store or in kit form with OE type parts. Basics are covered in the MA link below. Dr Diff offers the parts in kit form and is good to deal with IMO. The upgrade can be done with your current spindles or (better) with later 70's spindles which take bigger bearings. There are lots of upgrades beyond stock, but the stock parts work quite well, especially with 14" wheels.

I believe your current booster with new master will be OK with OE front calipers which have generous piston area. Some aftermarket calipers have smaller piston area and need more boost pressure.


http://www.moparaction.com/tech/archive/disc-main.html

http://www.doctordiff.com/brakes/