My 383 in my nova has always run oil pressure about the same numbers as you are running since it was built (me and dad built it) dad said that a sbc motor does fine at 5lb pressure idle and 30lb pressure going down the road thats fine (he was a mechanic for 30+ years and dirt track raced for years) so i trust his judgement, not saying your 406 is the same but just saying so maybe to sure your mind alittle