Like yeah sure it’s impressive that the C8 Z06 makes 670 horsepower from a 5.5L V8, but how about the 1974-1976 Cadillac DeVille making 190 horsepower from an 8.2L V8?
https://www.ultimatespecs.com/car-specs/Cadillac/29057/Cadillac-DeVille-IV-Coupe-82-V8.html
For comparison, in 1934 Chevy offered a 3.4L I6 with 80 horsepower, the same efficiency as that massive big block from 40 years later.
https://en.wikipedia.org/wiki/Chevrolet_Stovebolt_engine
The 472/500 was actually a fairly sophisticated design for the ‘60s. 400HP/550lbs-ft at its peak. The HP is kind of irrelevant with that engine because it was designed for low RPM torque.