Holley Air Horn Question

That’s ^^^^ funny.
I think the relationship between the air cleaner lid (especially with a drop base bottom) and the top of the choke horn and their proximity to each other, when installed and running in a car is where the big airflow differences will be seen.
Yeah, I've said this before, but in the 60s, GM had a huge R&D program on airflow and air cleaner design. When their patent finally ran out on what they were making, Moroso picked up and ran with it. Those old 14" Moroso air cleaners don't just look cool, they straighten, smooth and direct airflow right into the carburetor. You can look at most an GM air cleaner from the late 60s pretty much until EFI and see the design.