For reference only.

Here is a picture of the Carter AFB 9400s (400 CFM) on a GMC 300 (not mine).
Also the same model carburetor (mine) flipped so that you can see the small primaries and secondaries as well as the bolt pattern.
Also a clipping from 1978-79 Carter catalog showing STREET (modified++ from stock) engines.
Attachments
AFB 9400.jpg (66.06 KB, 222 downloads)
Bottom View.jpg (41.52 KB, 226 downloads)
Catalog Clip.jpg (70.78 KB, 225 downloads)

"Adding CFM to a truck will only help at engine speeds you don't want to use."
"I found there was nothing to gain beyond 400 CFM."