Most U.S. built 2nd and 3rd generation Chevy II/Novas had this cowl tag/VIN mismatch. You can throw 1965 into the mix, too. The cowl tags were all stamped as V/8 at Fisher Body early in the body build process and before it was known what engine would go in a specific car. The VINs were assigned once the car got to the Chevrolet assembly line and it was known whether a six or V/8 would be installed. Interestingly, cars produced in Canada never had this mismatch, probably because Fisher Body wasn't as separate an entity as it was in the U.S. Fisher eventually became more integrated in the U.S., when General Motors Assembly Division (GMAD) was formed.
Bob