If you are not an expert tube bender I would consider putting proportioning valve upstream of rear flex hose. You can hide proportioning valve somewhere behind rear seat. If you run too much tube up and down and have trouble bleeding high spot, you can add a high point tee for bleeding and for PSI gauge port.
Factory cars do have up and down runs; good to minimize these air catchers and to use small diameter tubes.
I have seen too many ugly brake line bends in the engine compartments.