Holley HP carb questions

My engine builder recommended a new HP 950 carb for my new roller 440. I've read on two different sites that these carbs don't flow what they're rated at. ( the 950 is supposed to be like an 830 and the 1000 an 870). I'm told that these carbs are tested at 2.06" instead of the industry standard of 1.5" and can be rated higher than actual. Anyone else heard about this? If not, what would be a comparable Demon carb? I haven't seen a Demon rated at 900+ except for the Race RS which is way too much money. Any help is appreciated. Engine should be done by Dec 10.