I've done this too. I took a 75 3/4 ton Chevy truck booster and made a bracket to mount it under the floor in the original position. I put a 66 Pontiac Catalina dual drum brake master on it to have the extra reliablity of a dual master. The fab work consisted of making an adjustable rod between the pedal level and the booster and replumbing the brake system. Also making the mounting bracket involved a little creativity, but nothing too difficult. Then all you have to do is run your vacuum line and bleed your brakes. This also makes your truck much more enjoyable to drive,
Scott
