i need help w/duster engine

the whole thing that started this. is..
if the heads potential at 266 cfm..(this part confuses me, is it 266 CFM?)
or is it supposed to be 2.66?
anyway..
if i do the math..266cfm head flow should give me 547hp ...pontentially..
i am only seeing 496 hp...sooo.. I think that if i get the cam correct i can get 547 hp...(rwhp)
Right..? I mean its technically there...
Mel.