340 Chugging instead of Reving

And you’ve removed the air cleaner, got it running and brought up the rpm’s to the trouble range and eyeballed as best possible that there’s no excessive fuel dribbling, bubbling out dumping etc from the bowl vents, or etc?

Yes. But I'm currently not running an air cleaner. I fired it up, reached inside the car to shut off the fuel pump, it only ran for 10 seconds as I gave it some throttle, I could see the initial spray of fuel when I hit the linkage, but I didn't see any other signs in those brief seconds. I don't have any help here to turn the pump off when it's in the trouble range.