I don't think they would really help that much on a normal 4bbl caburetor... too large of a diameter to really build any kind of velocity for harmonic tuning. If they DID do anything, I would have noticed it with the 2 foot long 5" hose on my ram-air setup.
Also, I think I remember seeing a test done by Car Kraft or Hot Rod magazine, where they compared no air filter, K&N stub stack, K&N High flow filter lid, and different combinations, and they found that a 14x4" air cleaner with the stub stack made a significant improvement over no air cleaner at all. Given that info, you might consider running an air cleaner vs. nothing at all, since you'll be saving your engine from dirt/debris AND adding some power.
This is true but I'm pretty sure Holley does'nt make a sub stack for a HP carb. Or do they? Which may not matter. I'd imagen that the base plate straightens the air flow a sufficient amount, the top of the 1000cfm HP main body is pretty smooth and flow friendly.