[Jeff Lee]

Another way of looking at the differences. A factory built performance muscle car from the '60's to 1970, the very best of the best, made 1 HP per cube approximately.
Most of your "bread and butter" muscle engines made around .75 HP per cube.
A modern Stocker version would not even be a serious engine unless it made in excess of 1.25 HP per cube.

And like everybody else has mentioned, it's a package deal. You can't compromise on one area.