Mechanical Pump with Return Line- input/pictures/etc.

Vapor loc in VA? what's your elevation there? and typical summer temps?
Do you experience it with all kinds of fuel?
I tell you what, I've never had a problem with that here in MB. Maybe cuz I run an AirGap and the carb gets fresh cold air from above the hoodline. I also run a solid line from the pump to the dual feed, except for a short jumper at the dual-feed. There is another very short jumper from the supply line to the pump,down by the framerail. And another back at the tank.All clamps are factory flat bandclamps, except the jumper at the dual-feed,where I have gearclamps two to a side with the screws staggered 180*. IMO,The factory had the right idea when they used those little flat spring clamps.
I say this because this works here in Manitoba, where the elevation is a little under 1000 ft, the summertime temps rarely exceed 95*, but can run there or near there for an entire month, with the nighttime temps about 10* cooler. and I burn 87E10 exclusively.
So what's the point?
Well I have found that mechanical fuelpumps suck air through single gearclamp connections more than one might think, and yet that same connection will not leak fuel.The jumper at the top of the tank is a "favorite".