What would it take to make 1.44 lbs-ft per cid ?

Dan the man said
Question: If a decent running 365 can make 450 horsepower which works out to 1.2329 horsepower per cubic inch. 1.440 x 365 = 525 horsepower. That's difference of 0.2071 horsepower per cubic inch of displacement. Did I calculate this correctly? If so, I don't understand why it would be so expensive to make the additional 0.2071 horsepower per cubic inch. I'm sure that I'm not understanding something here, but it seems to me that the extra power could be had with more compression and cam

If you look at average built 360's they make around 380 lbs-ft to about 450 lbs-ft that's 1.06-1.25 lbs-ft per cid, All out max effort engines can reach about 1.67 lbs-ft:cid, if you getting 1.20-1.30 lbs-ft your doing pretty good. Above 1.35 lbs-ft per cid is a fairly high goal.