I just did all of this work this weekend for a similar reason; I thought that my car was running out of fuel (starving/cutting out going up hills, seemed to void fuel pickup around corners, etc.). I had put in a new tank, sending unit, fuel line, fuel pump, etc. when I got the car running last fall; my non-AC car originally had the 1/4" return line (removed/destroyed when doing frame-up resto), but none of the repo parts places listed the 1/4" return line sending unit, fuel line, pump, etc. so I didn't put them in last fall.
Long story short, I ended up replacing the sending unit, pump, etc. AND installing the 1/4" return line this weekend. Didn't need to lift the engine (400ci) to route the line under the pulleys, just needed to disconnect the battery cables & remove the lower radiator hose from the pump. Going back to the tank, I had to remove e-brake line AND loosen the forward leaf spring shackle cover (to route the line under it). All day job (including siphoning the tank), but not too difficult. Not sure how hard it would be to route the actual fuel line, as it is much stiffer.
