Correct placement of proportion valve on '69 C20 front disc swap

[Caddylackn]

My truck had a disc swap when I bought it, but looks fairly hacked together, with lots of splices and adapter fittings. The prop valve is located on the frame behind the radiator. It still has the stock '69 master and brake booster.

I want to put the proper '71 master in it designed for front disc brakes and move the prop valve by the master and route the brake lines correctly but I need to know how a '71 C20 master, prop valve, and brake lines and brake line sizes.

What is the proper way to route the brake lines? The prop valve should be mounted by the booster. Is the prop valve from my '69 correct? or do I need one from a '71, or does a '69 not come with one and I already have the correct one?

Which side of the prop valve is for the front brakes, which for the rear?

I found this image but its not clear enough for me.