That's only 1.68 HP per cube. Although not easy certainly not impossible. From what I have been told by some one who was doing it after 2 HP per cube on pump gas it gets hard
It’s hard in my book but then again I’m a budget racer. No special ring pacs, no vacuum pump, no line bore, no torque plate, no lightweight parts, shift at 6800 rpm, no special valves, home ported junk, probably a smaller carb than most would run, Chinese parts, self assembled, no dyno tuning, etc.