Its also important to note that pre -72 horsepower standard legal SAE testing was bare engine no accessories no exhaust and post -72 standard legal SAE testing

Its also important to note that pre -72 horsepower standard legal SAE testing was bare engine no accessories no exhaust and post -72 standard legal SAE testing was "more or less wheel dyno". So it was not unusual at all for something like a caddy to go from 400 gross HP with no exhaust no water pump no cooling system nothing to 250 HP pushed out the wheels. Now a caddy has a ridiculous exhaust and addons, but even a vette has some. Its highly likely that the 270 HP bare engine and the 190 HP car are the same. Another complication is HP = torque * RPM I had a commuter car in the 80s with a 2.2L engine that on paper only output 100 HP because its redline was something ridiculous to modern standards like 4000 rpm however the torque (acceleration) was huge compared to my current 100 HP commuter car that winds up like a motorcycle to 8000 RPM or whatever it is. My current car has the acceleration of a 50 HP car but the redline has doubled, so...