The 350 H.O. Deluxe engine that we tested came from GM Performance Parts complete with a 600-cfm Holley carb, dual-plane intake, HEI distributor, spark plugs, wires, even a water pump. With iron Vortec heads and a mild cam, Chevy rates this engine at 330 hp. With headers and mufflers, our 350 H.O. made 348 hp at 5,200 and 388 lb-ft of torque at 4,000.