Hyper Pak Intake with 350cfm 2bbl To much for a 225 Street Slant Six?

scamperly said
If you're simply streeting it, perhaps seek out an offenhauser intake or something of the like, no need to spend the money on a hyper pak. If money is of no concern though, go for it. I'd say, perhaps a small 4bbl, like a 390cfm, so that way you run on the primaries most of the time, and when it's WOT you can still have fun. The 2bbl will always be pumping in 350cfm, where as a 4bbl will be doing a lot less when you don't need that much fuel being pumped in.

Basics:
A Carb is a simple, yet complex fuel metering device that uses the difference in pressure above and below the venturi (s) to pull fuel into the air stream through a series of metering orifices. It doesn't matter what type or brand the Carb is or even what size they all work basically the same way.
If you are using the common Carb Manufacturer's formula to determine the Cubic Feet per Minute (CFM) requirement for your engine:

CFM = Cubic Inches x RPM / 2 / 1728
Where:
CFM: Cubic Feet per Minute, of air flow.
Cubic Inches: the Engine Size.
RPM: The RPM that you want to know the flow at.
Generally this will be the maximum RPM that you intend the engine to see.
2: corrects for the 4 stroke nature of our engines.
1728: a constant that turns Cubic Inches in to Cubic Feet

You must accept that the results are intended to select a Carb for a 100% Volumetrically Efficient engine. Volumetric Efficiency (VE) is the measure of the engines breathing efficiency. Race engines can reach VE's that exceed 100% while most street engines are between 65 an 80% with some well tuned street engines in the 90% VE range.
You can not directly compare the CFM rating between 2BBL's and 4BBL's as the test pressure that is used to measure the CFM is different between the two. The 4BBL is measured at a test pressure of 1.5 inches of Mercury (Hg) of pressure drop, while the 2BBL is rated at 3 inches HG. To convert the 2BBL into 4BBL use the following formula: 4BBL Flow = 2BBL Flow / 1.414.

So that 350 CFM 2BBL Carb actually flows 248 CFM on the 4BBL scale & a 390 CFM 4bbl flows 552 CFM on the 2bbl scale.