What is the red line in a 1965 289 K code hypo?

I assume that "redline " is the max rev per min!? If its stock your only limited by the valve springs on the valves. These motors were built strong ( forged cranks, hardened rods) made for racing thus making the redline when the valves start to float. Stronger springs = higher rpms! I've seen these motors easily reach 9000 rpm