I'm no expert, but as far as I can tell the Holley 94's are around 175 cfm but rated at 3 inches of vacuum instead of the 1 1/2 inches used to rate 4 barrel carburetors. So if I have it right, you would take your total combined cfm and multiply it by 70.71% to get the 4 barrel figures. 175x6=1050 cfm/1050x.7071=742.455 cfm. I'm just going by what I read on this post http://www.jalopyjournal.com/forum/showthread.php?t=327843&highlight=cfm+ratings .
That is the 3 bolt base carb that looks a lot like the Stromburg 97. I've had them on old Fords I've owned. A flathead in a 53 F100 and a 272 Y-block 55. Here is a good article on these carbs from Classic Truck magazine. Check it out, it may answer most of your questions. http://www.classictrucks.com/tech/0803ct_holley_94_carburetor/index.html
That's a good read! Thanks for posting that, it really gets into the nuts and bolts of those Holleys.