440 source engine packages

What puzzles me is, they have these high dollar stroker motors putting out like 1.32 horsepower per cubic inch. I wish I had the dyno sheet on a 0.030 over 289 with edelbrock e heads, performer 289 intake, 650 Holley, comp 268h cam, 8.62:1 cr. It made 303 horsepower at 5900 rpm's. So my question is, how can a little 289 make almost as much power per cubic inch as some of those high dollar stroker builds?