K-H brake swap done, but doesnt stop!

I have had these calipers since 1980, (when I bought my Barracuda Convertible) they are prone to sticking, you bought these 15 years ago?? check the pistons, there were alot of them produced with a chrome plated piston. The chrome plating will rust off of these pistons and stick them in the holes, make sure if you have them to replace them with plain steel ones, they last longer and work smoother.... hope this is helpful.