You want the P-47M.hps file. The easy fix is to take the headset off, hold the keypad or hat for the rear view then press the Home key to reset the rear view and F10 to save it.
You can also just move your head, wearing the headset, to center the rear view then save it with F10.
AH3 has a folder of default hps files. If you delete your hps files from the planes folder I believe the game will install the defaults. You can delete the default *.hps files if you don't want any of the pre-set head positions.