go and find an escort rst master cylinder and servo, replace the fiesta one with this

the escort one is used to push bigger calipers than the fiesta one so will have a larger bore to push more fluid around the system

the cossie 4 pots need more fluid in them to work the same otherwise youhave a longer pedal

just make sure you uprate the rears at the same time as you will notice the difference if your car starts to swap ends every time otyu press the pedal