340 4 barrel and 340 6 barrel: were they really UNDERrated?

The 340's were a SCAT PAC. My understanding, that meant they were in the 13.99 or better range. I still have somewhere, ads from the factory that say the 340's are a high 13 car in the "A" bodies. Also $2,800 for a 2800 lb. car. A dollar a pound.
Scat pak was for any car that was quicker than 15 sec quarter mile, from my understanding.