A stock 350 motor can have as little as 145 horsepower and up to 370 horsepower in the LT1 model that was stock in the late 1960 Corvette. The Chevy stock 350 motor had a huge decrease in performance during the 1970's fuel shortage.
The displacement on all the motors is the same, but the LT1 featured a tuned and well-rounded performance fuel and exhaust system. An engine code located on the back or side of the block can be used to determine the motor's manufacture date and performance capability. The Modern Chevy 350 makes around 250 horsepower and is relatively fuel efficient compared to older models.