I'm assuming you mean to tranfer ALL the 70 Mustang Disc brakes to the 69.I'm gonna install 1970 power disc brakes onto my '69 Mustang. The '69 has factory drum brakes all around. Will I need a different brake pedal to do this conversion?
Correct. The 67-69 booster had a teardrop eye at the pedal end. The 70 had a straight eye. Naturally, the pin on the 70 pedal was slightly higher to match this. Don't mix them, if you force 69 and 70 parts together, assuming it works at all, it'll be quite unsafe.