I've had several nearly identicle 440 bracket motors, same cam, same heads, same pistons and compression ratio, the only differences was the 6 pak rod versus the standard LY 440 rod. The 6 pak rod motor didn't like to pull as hard above 6000 RPM as the LY rod motors did There are several rules that apply to race motors, big is best, C.I. cam, heads, carbs. and intake, compression ratio and a few others Another one apllys to motors and cars, lightweigh is right, rods, pistons, wheels and tires, drivetrain components and a few others Those six pak rods are overkill