Quincy model 120 air compressor CFM ?

This is my latest auction sale find that I just installed in my farm shop.
It is an 80 gallon horizontal tank with the Quincy 120 compressor. Tanks on the compressor and tank say Quincy, although the machine carrys the SURGE milking equipment orange color and decal. The "surge" compressor supplied air for a dairy milking parlor where most gates,feeders, doors were operated by air cylinders.
The thing is 40 years old, but so smooth and quiet running with it's pressure oiled compressor with gauge that indicates 15 psi oil pressure and air operated unloader system that uses tank pressure and (I think) compressor oil pressure operated valve to disable the intake valves during starting.

It seems to do much better than the 6 cfm spec I found earlier, or is the 20 gallon Sanborn portable compressor it replaces that I have used since 1968, just that tired ?? TIA

• Quincy