Adding a new adjustable prop valve involves cutting the lines and flaring them to attach to said valve. It is easy to do. With plain old drums in the back it’s not something Uber critical. Hell you could simply not use a prop valve at all. People have done it without issue. The main thing you are trying to do is prevent rear lock up before the fronts engage. Majority of the braking power is in the front discs. These cars are freaking dinosaurs with 50 year old brake technology. The factory made it work just fine with OEM parts. Aftermarket prop valve has its advantages but not necessary. I have one of them sitting In a box if I ever decide to put rear discs on my car. Only then will I switch out the later proportioning valve and reinstall my old drum distribution block.
Try not to make this more difficult than it needs to be. You are not getting misinformation. You are misunderstanding the information given. Take your time and read up. We are happy to help fellow members so please don’t take this the wrong way.
