Not to be a geek, but horsepower is not directly proportional to torque and RPM. As the torque moves up in the RPM band, the horsepower increases at a rate greater than a simple multiplication. I want to say that it increases exponentially, but I don't have the formula in front of me so I can't verify that.

In other words 100 ft/lbs at 4,000 RPM would not produce twice the horsepower of 100 ft/lbs at 2,000 RPM, it would be something greater than double.

There was also a reference to increased compression ratios and engine life. There were many cars of the sixties with 10.5:1 or greater compression ratios. Increasing the CR makes the engine more efficient, therefore, theoretically it should waste less energy in the form of heat. Thus, in theory, a lower CR would not lead to a longer lived engine, unless there was a structural defect that led to a failure.

Have a great day,
Larry the Geek