15 pounds of boost huh? What's your SCR? Even as low as 8.5:1, you realize your effective c.r. will be 17.8:1? You won't do it on 92 pump gas, even with meth injection you'd be pushing it.
To make 12.1 pounds of boost in a 540 motor you would need to overdrive an 8-71 30%, I'd estimate a 572 will require at least 40% overdriven to get 15 pounds. 1:1 in a 540 will make 6 pounds.