Holley 4bbl carb

It's a 4160 type due to the lack of secondary metering block (4160 uses a non adjustable plate instead). You can make a reasonable size (factory CFM) guess if you measure the throttle blade diameters although the venturi size that ultimately determines flow through the throttle blades.
Rough guess; it probably started life as a 3310-2 750 CFM before someone cut the choke horn off.