Matt, I know you've seen this formula for cfm/boost before. Let's look at it again....

The size of carb(s) or CFM required for a given application can be calculated by the following formula A: {(CID x RPM) ÷ 3456} x {Boost ÷ 14.7) + 1} = CFM required. The amount of CFM required will determine carburetor size and quantity. If you try to use a carb with less CFM than required, performance and economy may be greatly reduced.

Using this formula and plugging in 200 cid, 5,000 rpm's and 6 lbs of boost, you find that you will need 404 cfm. With 6 lbs of boost and 8.4 static c.r., your final compression ratio under boost will be 12.0:1, the limit for pump gas.

What you're interested in is a blow-thru system where the turbo only compresses air and the carb is reworked to withstand the pressure. Spend the dime and call these guys and get the straight scoop, then report back here please. I'd like to know what they have to say.
http://www.performancecarburetors.com/blowthru.htm