Thanks - I'd much rather talk about engines than argue.
My objection wasn't that you want traditional appearance, it's that you're making (what appears to me to be) extra work for yourself. The B (or M?) has too many variations to know which body casting is best, tuning parts not easy to get.
Repeating the math: 292" @ 90% VE, 5,500 RPM (adjust as needed), is about 460 CFM. 10 psi is 1.68:1 pressure ratio, makes 772 CFM just to get 1.5" Hg vacuum. If you're jetting is good, you could run even more area down to perhaps 1.0" Hg. Even 4 needs 193 CFM each, only the largest 230 & 292 1-3/4" models are that big. It does allow progressive to keep the idle and low speed clean, though - idle on a center pair with the outers as secondaries.
IIRC they have power valves and an extra-fuel passage, don't know if it has a jet or just a drilling. I'm not sure how to reference the power system except by drilling through the body casting (this information is well-known for Holley and AFB), or address the fuel curve for extra gas on boost. This is a very ambitious project, but as we all know they have a tendency to add 2 new thoughts to the end as 1 gets taken care of - it never stops.
Cam: looks good, may need some tweaking.
You're going to need some serious work on the pan just because of the high power - scraper, baffle, pick-up surround, potentially lowered sump and extended pick-up. This doesn't even really need to be done until after the engine is built, especially since it has to match the chassis.
Headers: BIG primaries, the size is based on the power output, not the cylinder or valve size. 400 hp ÷ 6 needs the same as 533 ÷ 8, you may need 2" OD.
The intake shape can be a big advantage. The most current 14-71 blowers have their manifold inlets near the front of the case (like an Eaton), not centered in the rotor length (as did all older GMC manifolds). This both increases flow, improves distribution, and lowers charge temperature. You may need to make a jack-shaft to position the nose drive where your crank pulley can reach it.
