Thanks for the honest answer Dwayne. I'm not ashamed of it falling short, was my first 'real' engine build, can't expect perfection first time around. Could be there's more to this engine building stuff than meet the eye. Seems like part one of the challenge is to make it run but part 2 is to make it run good.
David Vizard says if you can net 1.35 ft/lbs. per cube the combo is efficient. In the case of my 416", that would be 561 ft./lbs. so based on that somewhat arbitrary (though based on lots of experience) number, I'm way off.
Not to make this all about my under-performing combo but it seems my main question here is not about how much head flow will produce X amount of power but instead how to best utilize the given flow of a set of heads to achieve maximum potential. It's the age-old question I guess. Obviously the set of heads I have hold the potential to make more power but for whatever reason(s) they're not.