The heads were lazy pieces of ****.
There is no way you need that much port volume to flow those "advertised" numbers. I can get the 205 versions advertised flow at 180-185cc with an iron head. Also the one size fits all exhaust, how big was that port?
Too much port makes for a lazy torqueless pos.
He should have done 185-190 with some room to work. Hell...raise the roof, sell an intake spacer....mopar did it and it worked within stock constaints.