Rear brake line routing

[Jimal]

As I continue to dig into my '65 K10 short bed, the more I'm realizing I've traded fixing things like rust for fixing weird things the PO did. Case in point, the rear brake plumbing. The guy I bought the truck kept the four-wheel drums but upgraded to a dual circuit master cylinder. It looks like some of the original hard lines remain, mainly from the rubber line out back forward to some point under the truck, where it was spliced into new(er) line, which crosses under the crossmember that looks like it will have to come out when I tackle the flywheel replacement. Is this the correct crossover point? I've flushed the lines out so I should be good to go with the rear brakes once I install the new wheel cylinders, but at this point some I'm inclined to throw some new hard lines under there just for good measure. If not along that crossmember, where should the rear brake line cross from the driver side to the passenger side?