I emailed Holley about this pump and told them to give me some straight talk. 2 weeks ago. No response. So, it is still on order. I am still having the issue. Hot weather, the pressure tanks to 0, sometimes at the top of first gear, other times in 2nd. IDK what I am gonna do yet. I might return it, or try to install it, maybe run all new lines too. Maybe mount an external noisy pump with a regulator.
My fuel pressure gauge has a sending unit plumbed into the 3/8 fuel line, 8" before the carb, with the gauge itself in the car.