It started off as a hypothetical but the OP is figuring out the best heads for a 650 hp 493, PRH already gave the answer.
I disagree, yes peak ve will occur at peak torque but rpm is lower, at peak hp ve will be down but more rpm so should be flow more air overall, just less per cycle.
I'm not making a statement about where peak air flow occurs, I made the statement to use the equation where peak VE occurs. After all, the equation even has a peak VE number in it.