4 Barrel on a stock slant

Drivability is all about the primaries. Restriction only comes into play at wide open throttle. The stock 1bbl on the six provides decent economy and drivability, but is incredibly restrictive at wide open throttle. Based on this, a progressive 2bbl carb would be perfect, but who makes one? The BBD 2bbl can be tuned for decent drivability and similar economy, and at least has some headroom for WOT. IME it vastly improves passing and hillclimbing power on an otherwise stock engine (I do have the larger exhaust manifold exit and a bigger pipe). But the only way to get a progressive carburetor is with a 4bbl. At least in theory, this should work so long as the primaries are not too large, and you can jet them lean enough. If the secondaries are too big, so what? The engine will pull what it can flow, and there won't be any restriction; again the only issue is to keep from flooding it. I would think the AFB from a 273 Commando might work -- it has small primaries, and is tuned for a small port engine. The one thing about a 4bbl is, you would ideally want it mounted sideways, so the primaries are facing the head (to ensure even mixture across the cylinders.) That makes for wacky linkages. Or you could use a big plenum. I don't know what the Offy intake looks like inside.