My car has the Charger style flip cap that says fuel on it. I'd say that thing is kn b not air tight. ShouldX ls suffice for a low pressure return.
I've actually been messing with cars since '85. They were always Chevies though. My 'Cuda is the first one I attempted silly go fast stuff with. All of my problems started when I installed the pro comp heads and a .570" solid roller camshaft. What went from simple bolt-on parts all of the sudden became very critical tolerances and high preasure this and extreme duty that. I was always used to simple flat tappet cams and iron heads. Still not a fan of torsion bars or Mopar ignition systems. Lol!
