If I am not mistaken, during rotation to a two-point attitude in a tailwheel aircraft like the Mustang, P-factor is initially and briefly reversed (with an effective shift from a high angle of attack in the three point attitude to near-zero once up on the mains), then resumes the expected left turning tendency once the mains lift off the ground and the positive angle of attack (and accompanying change in propeller blade angle relative to the relative wind) is reestablished. Granted, engine torque is going to be applying a normal left turning tendency this whole time, but during rotation the net forces rapidly and briefly change quite a bit.
The latest update did change things for me, too, but not to an unreasonable extent. I am a chicken though and rarely use anywhere near full power for takeoff in the 'Stang.
The forces acting on a Mustang takeoff (all tail wheels) vary both in affected axis and intensity.
Initially from a standing start the predominant forces are slipstream against the vertical stabilizer and rudder area and P Factor due to the angular difference between the prop arc and the relative wind. These two forces are in yaw and a right rudder correction.
As the takeoff continues and the tail comes up you get gyroscopic precession 90 degrees ahead of the prop disk which adds more yaw to the right rudder correction. There is an easing of the P Factor as the prop disk aligns more evenly with the relative wind. Now as speed increases you get dynamic pressure on the ailerons. Torque has been in effect since power came up but torque is a ROLL correction requiring right aileron. As speed comes on line and you have aileron authority you begin countering torque with right aileron.
As you rotate the airplane you again get gyroscopic precession but this time it's reversed. You also reacquire P Factor during the rotation until the prop disk again aligns with the relative wind. You have slipstream forces active throughout the takeoff and into the climb. The reverse gyroscopic precession at rotation isn't a prevailing force condition as the rotation of the axis is minor and the aircraft quickly stabilizes in climb. The left turning forces prevail even through rotation.
So all added up together what you have in control corrections in a tail wheel aircraft takeoff is a combination of right rudder and right aileron applied as dynamic pressure becomes available.
It's for this reason you should NEVER raise the tail on a tail wheel airplane EARLY in the run. Just let the tail come up naturally. This is ESPECIALLY important in an extremely powerful aircraft swinging a huge prop like a Mustang!