Dick Whittingham - If I'm reading the Merlin 22/24 power chart correctly, at sea level and 1800rpm max boost was +6 giving 675HP. At 3000rpm max boost was +18 giving 1620HP.
The formula is
Power(hp)=torque(ft.lbs)*rotational speed(rpm)/5252
I'll let you do the maths.
As an aside, before we went to the carrier for the first time the instructors showed a vid of prop operations on a carrier. One spectacular sight was the F4U's launching and immediately rolling in 60° of left bank on leaving the deck. We thought it just a little of the macho showing, but instructors advised it was torque in control and pilot was just along for the ride until a bit of airspeed was gained, and hence aileron control.