Prop valve line routing

[Eagar1]

Getting ready to mount my brake booster/mastcyl/propvalve, thought I knew how it should be routed then I came across this picture, on a 70's truck that looks like the same mast cylinder I have, and a similar valve. The routing in the picture looks backwards to me. I have a valve off a 75 C10 that was disc/drum. It is just like the diagram shown. Also wondering what the difference is if I plug the top front hole of the prop valve for the front brake(right front) and just T off the lower one(left front) instead of running two seperate lines? Also is there any reason why I couldn't run the rear brake line down the driver's side? Seems odd to run it over the front crossmember for no reason.