[Bruce Edwards]

The size should be cast in to the side of the master. If you went to a larger brake set up and the pedal feels better than before with the smaller brakes I am not sure what your problem could be. If your masters were to small to start with going to a larger set up would have made it worse not better.
Have you tried a quick stop to see what brakes are working or is just that they feel soft? When you say "soft pedal" do you mean it takes little effort to push it or it feels like it has air in it?