Unless you have verifyable history, I would replace the master cylinder with eith a new unit or there is a rebuilder back east who is very good utilizing stainless steel sleeves, replace/rebuild the wheel cylinders, replace all springs, wheelbearings, etc. I would not purchase any composite brake drum, whether they are distributed by Bendix, Raybestos or TRW they are all made in China and do not meet DOT specs...IE very, very dangerous. Check with Kanter auto, I think they can get you real steel units or call CarboTech Engineering in Florida (web site also) to get cryo dipped drums (costs about $15 each more). Brake linings...whole other subject..
Your Mustang was designed for semi-metallic linings with a friction co-efficient of .25 (IIRR) or better. The shoes sold at the local parts houses do not meet this spec...ie you can get yourself in real trouble, just because they say "DOT" approved, doesn't mean they are approved for that application. Replacement linings are available in semi metallic from L&N Friction Riverside Ca, ($50 a set) of you can get higher level friction from CarboTech engineering ($120 set). Also, make sure you have fro the fronts the "Brake shoe retracting assist spring", it is not included in the brake rebuilding kits now, but it connects directly the primary & secondary front shoes together. Without it, the front shoes will drag against the drums causing excessive wear out and dragging