Yeah I put an "L" shape on the back of the bracket so it would contact the rail and bite in a little to stop movement but a fastener or dowel would work better.
I want to re-use most of the engine bay brake lines if they come up nice after a clean and some plating, I will remake new front hard line to the calipers though. I am going to modify the front to rear brake line so that it will come straight out of a proportioning valve in the engine bay and heads down to the diff. Then I am going to make a small hard line to go from the brake pressure warning valve to the proportioning valve.
My plan for the diff is to have hard lines running from a T piece on top of the diff to the tramp rod brackets, and have a tab mounted to that bracket and braided lines from there to the calipers.
That's the plan as it stands at the moment so it gets through engineering retaining original safety equipment (even though they don't really work).