I used the ChevyDuty kit to do this on my '55 1st GMC. I later decided that it was the same kit available from Clasic Performance Products for about $15 less.
I bought the appropriate residual valves for a drum/disk system, and spent one whole Saturday replacing all the brake lines.
I had one leak that proved to be a poorly done flair.
I have a continuing problem with the brake pedal not returning all the way to the top under some circumstances.
In my case it only occurs when I've made a hard right turn, and I've developed a habit of lifting the pedal with my foot after hard rights. There is only one corner like that on my usual path, so its not a big deal.
It doesn't hold the brakes applied, but it does leave the brake lights on.
I've concluded that I need to replace the body mount to better control movement of the body, but I've not done anything about it yet. The problem might not exist at all if the rod was aligned a little better. I'm not sure what it would take to fix that issue.
