70 Duster power to manual brake conversion
If you have a manual brake master cylinder, everything will bolt up.
If the push-rod appears to be 1" too long, it is probably not bottomed out inside the master cylinder piston.
Did you install the rubber clip on the end of the push-rod and insert it into the piston? Is the push-rod locked to the piston?
Did you re-adjust the brake light switch? The pedal is much closer to the floor on power brake cars.