* The engine code: This is usually a letter-number combination stamped on the engine itself (often on the block near the distributor). This code will pinpoint the exact engine variant.
* The original owner's manual: This will list the horsepower for the specific engine installed in the vehicle.
* The vehicle's build sheet (if available): This document, sometimes found with older cars, details the specifications at the time of manufacture.
Without this specific information, it's impossible to give a definitive horsepower figure. The 350 Rocket ranged from approximately 175 to 260 horsepower in 1972, depending on the carburetor, compression ratio, and other factors.