During the early days of "Super Stock" as a drag racing class, various sanctioning bodies (NHRA, AHRA, IHRA, NASCAR, plus an array of local entities) offered a variety of categories under the label "Super Stock." By 1967, NHRA had pretty much locked in a set of rules that defined "Super Stock" as a car that had been produced in quantities of at least 50 units and was available to the general public.
In 1966 and '67 Ford offered the 427 Fairlane as a viable option for Super Stock. Some were equipped with a lightweight, scooped hood and there were a few "Tunnel Ram" versions around. Eventually, Ford developed the 1968 Cobra Jet Mustang and and introduced a flock of them in Super Stock at the 1968 NHRA Winternationals.
In 1968, Chrysler pushed the limit of the Super Stock rules by commissioning the construction of 50 Barracudas and 50 Darts equipped with lightweight body parts and the "race Hemi" powerplant that had originally been developed for the 1964 and '65 A/FX cars that kicked off the "Funny Car" craze.
In 1967, General Motors added the 375 horsepower 396 (aluminum and iron-headed versions) to the Camaro line in order to stay in the game. Two years later, GM moved further into the market with the low-production COPO 1969 Camaro and Chevelle and eventually the ZL1. While some Camaros competed in the lower classes of Super Stock with the 350, 295 horsepower engine, the 327, 275 horsepower engine, and the 1966 327, 350 horsepower Nova was available, they were close to the bottom of the class structure that originally stopped at SS/I and SS/IA.
In the final analysis, the car you have described is what it is. In NHRA, many first generation Camaros, Novas, and Chevelles competed in Super Stock with the 327, 275 horsepower motor, especially after the class was broadly expanded in 1972, and if the car was campaigned as a "Super Stocker" under the rules of one of the sanctioning bodies other than NHRA, all bets are off. Their class descriptions could have easily accommodated combinations that were never produced or sold.
We'll all be interested to see what you find.