No, the WCFB's are not rare by any means. Also, many of the Pontiac OHC 250 engines had Quadrajets on them and were very driveable and had good street manners. The idea of improved air signal is one reason why that design of a spreadbore carb works good because of its greatly reduced primary bore size. Given that, a Holley 650 spreadbore carb would likely be a better street performer on many of these 6 cylinder engines including the 250's and 292's than a Holley 600 squarebore carb. Even though overall it flows a higher total CFM, simply because it utilizes that design of smaller primary vs. secondary throttle bores to be more responsive, efficient and driveable in slow street driving RPM's. One thing that is often overlooked today and in times past with hotrodders is using the right part for the job, many do not. Also, Holley invented the 3 bbl back in the early 1970's, not Tom.
