I think you're missing about 100 hp from what that combo should have. You might want to start by just doing all the usual checks. Run the lash just to make sure you haven't lost a lobe. Check the cranking compression, check your ignition system, run a fuel flow test, etc.

A 440 with those parts should make about 550 hp but your ET, MPH and Weight say that you're making about 450 hp.