I went through pressure loss problems when I was setting up my 68 Hemi Runner. Even with the factory .060" return I had about 1.5-2 psi loss from when the line was clamped closed. I soldered the opening and with a little trial and error, I ended up with a .035"ish opening and with just a slight loss in pressure but still allowing enough flow to keep the function. I have had no issues in the past ten years or so with vapor lock but I also used a couple short pieces of insulation around the fuel line where it has close proximity to the exhaust pipe.
This may or may not work for you but keep in mind that you might need to make small modifications to enhance the OEM function.

68jim