My fixture flows carb bodies one barrel at a time..... Which isn't really correct either........ But unless you have a 1200cfm bench...... You do what ya gotta do.

For an approximate wet flow number, I take the dry flow and use .92 of that.

Flowing one barrel at a time, and using the 92% number, an original Holley HP950 (1.375 x 1.750) flows about 860cfm.
Traditional Holley 650's, 750's, 850's(with the chokes) come out pretty close to their respective ratings when tested that way.
The same cannot be said for most of what I'll call the "new design" carbs.