Brake pedal travel

[66_k10_manny]

Just installed front disc brakes with mc and booster on my 66k10. The mc and booster come from a 97 blazer. Brakes are working great but my pedal drops down almost to the floor board. Thought i might have a bad booster so i swapped it out yesterday and no change. The brakes start grabbing with the pedal pushed about 1/3 of the way down and then full grab at about 2/3 down. With the engine off, if i pump the brake pedal, it firms up and stops at about half way down. If i then fire the engine up, the pedal drops down the rest of the way. May be this is the normal travel? Anyone have ideas or suggestions?