Adding power brakes to these particular trucks is very simple. To start find a donor vehicle in good shape and you can proceed one of two ways to do the swap. The first you can remove the entire front crossmember unit and bolt it to the underside of the older 63-66 gmc frames. the other way if you prefer the original suspension arms and brackets involves getting the spindles from the newer truck and having newer ball joints from the donor truck year installed into the a frame arms. once that is done you can bolt up the newer brakes easily. the newer ball joints are a shade longer than the originals so you at least need a set of those. The upper ball joints are identical in length and bolt pattern.
Power Steering Conversions
To do the power steering conversion for the truck I went with a REZ Engineering power steering conversion kit. They claimed it was an easily performed modification that did not require welding to the frame. I have to say the kit was excellent after about three hours I had a new power steering box installed on the truck. Make sure to use the original center steering bar the newer bars mount and fit to close to the older crossmember. When it is all completed it came out that the idler arm was at most a 1/4" off the original factory specs which is quite a feat that it came out so close to the original specs, considering you have 1/8 inch spacers between the new plate and the steering box.
I later have plans to purchase a Ididit steering column and borgensen shaft assembly to connect the box and steering column.