I installed power brakes on my 66. I moved the rod to the bottom hole, adjusted the brake light switch all the way out. The spring and bracket is installed and the rod is adjusted all the way out. The brakes aren't dragging. Brakes work great, problem is that the pedal isn't returning all the way back and hitting the switch. Lacking about 1/8". Do I need a stronger return spring in the booster? The pedal travels free when the rod isn't attached. Thanks, Tom

You should be able to push the brake light switch assembly further into its bracket, moving the switch closer to the pedal.

I had to do this as I switched from atuto to manual trans and therefore needed the appropriate pedals. My auto brake pedal had a tab attached that contacted the light switch. The manual pedal did not have that tab and I had to make up the distance by pushing the switch in further.

Tim.

Tim,
Thanks for the reply. I've got the switch adjusted all the way out. I even took off the nut on the outside-trying to get a little more. Still too short-story of my life:). I'm going to make a bracket and attach it to the pedal. Thanks again, Tom

The later year power brake cars came with a bracket that screwed on the the pedal called a striker. The striker was added to correct the problem you are having. The shape of the striker depended on what model GM produced due the the shape of the pedal. Probably can make something or get a striker from a later vehicle and make it fit.
BTW
You can remove the return spring. Chevelles with power brakes didn't have them. The booster returns the pedal.