I had a 1971 440 warranty short block and it had HP stamped on the ID pad. Keep in mind this was a HP motor and had the heavy six pack rods and would have been different from a standard production 440. That would likely be the reason for the need identifying a HP from a standard production motor. A 383 engine may be a different case if the internals are the same for 2 bbl, 4 bbl and HP engines.