nice pics, that explains a lot for those who see your truck for the first time. looks like you have a start with the tools. the bending pliers will tend to kink the line if youre not careful. i use them for close to fittings only when i can't get the other style to fit. there are a few videos showing the tubing bending theories. try a few flares on scrap line till you are confident you have it down to a science. here is a common bender for smooth bends in the open areas of the tubing that allow the tool to fit in.
https://www.eastwood.com/tubing-bend...liers-kit.html
https://www.youtube.com/watch?v=ulc6tiFX6H0
with your set up it is common to attach the prop valve under the master cyl just for ease of running the lines. it could be on the frame out of site though. an adjustable prop valve is nice but once set it is forgotten about unless there are problems or changes made to the system. just ensure the master cyl is one for a disc disc set up as well. a residual valve may be pressed into the master on the drum brake port otherwise and that will give you grief unless it is removed. not sure what the master came from.
have you checked your pinion angle and compared to the trans output? it looks like it is pointing downward a lot. could be the pic./ pinion angle should be equal but opposite to the trans output within a degree or otherwise you are asking for vibration especially with the offset diff center section.