When I had vapourising problems the car started splutering. I thought the car had run out of fuel. The car would surge then splutter and nearly stall then surge again. The motor was not efi (1000cfm Carter).
Running the return line to the tank may/may not as the fuel will be vapourising on the way in (if indeed vapourising is the problem)
It might be worth putting your hand on your swirl pot
.....to see if it feels hot to the touch (obviously after the engine has been running for a while)
If you want to run a test I suggest you get some rubber fuel line and run a temporary fuel line to the engine routing it well away from any heat source.
Unfortunately the hose is expensive but it might be worth a try if time is limited.
As you know I have the same motor as you in my Cobra. I am running an in tank fuel pump (ford EB) and my fuel lines run through the wheel arch and into the chasis frame on the side of the car (miles from the under car exhaust). The motor runs fine.