1968 '340' Barracuda vs 1968 '383' Road Runner

The factory ratings were almost never over estimates. They could get sued (and did) for that. They also weren't usually off what they claimed. What usually was the case in an under rated motor is it wasn't finished pulling at the RPM the HP was published.
So the 383 although in the heavier car did make more torque even if HP was close. It also made it early and constant. In modern 5 and 6 speed cars where you can keep the powerband up HP rules, but on a 3 speed auto I would like the torque.