Brake pedal issues after installing power unit

All I can tell you is I put power brakes on my 63.
I did have to modify my brake lever from the pedal to the booster by cutting a section out and re-welding it to achieve proper pedal height. After I had thought about making the lever slotted and having it adjustable.As far as pedal not returning try loosening the attaching bolts and see if it's a alignment problem causing binding.