Return fuel system w/ current parts?
Was it me, oh wait it sorta was, I'd ditch the P4070 variant and the mechanical pump both. Replace them with something like this:
http://www.summitracing.com/parts/vpn-gsl392bx/overview/ Run your choice of by-passing regulator in the engine bay. Run a new 3/8" supply line and use the original supply line for the return line.
'65 Valiant-
Pump location:
Regulator location:
Now that I'm not running the Mopar IGN module I wish that I had made a plate that replaced the module for the regulator to bolt to.