Brake pedal travel is to high/play

Sorry about lack of info on the car. 1973 /6-225 Automatic Duster at the moment. After my son gets some experience under his belt we will be dropping in a V8 or modding and rebuilding the slat 6. The rest of the car is finished except for a drivers door panel and swapping out the rearend. It has the 5 on 4 bolt pattern and we had to use a 5 on 4-1/2 adapter to put the wheels he wanted on it which moves the tires in danger range of the wheel well lips if the airshock decide to exhale. The brake conversion is from a full kit and I dont remember who from. I have the manual and can reference it if needed.
Looking at the parts listing it appears that the only difference is manual or auto trans for both the pedal and shaft. doesnt seem to be any difference between power and non power brakes. It is an original auto slat six car so it should have the correct parts already in it.
I really appreciate the help and fast responses guy.