Should length of pull be different for a turkey gun? If a 13.5'' stock fits me normally, should it be shorter for turkey hunting because I know in this type of hunting you can find yourself in awkward shooting positions.
Never thought much about it and have never had a problem shooting my regular wing shooting guns for turkeys.
I think your lop should be fine. I personally like a pistol grip (AR type) stock but they aren't for everyone. I find it makes waiting out a bird a little easier for me. I stay more comfortable and tend to move less. Could be all in my head though.
When shouldering your conventional sporting stock shotgun there should be two fingers width between the back of your thumb and your nose. The reason for this is obvious, you don't want recoil bloodying your nose with your thumb. This holds for whatever your using the shotgun for. The proper LOP for you is what ever length permits this two finger width. Now if you opt for a pistol grip shotgun for your turkey gun you can get away with a LOP one inch shorter because your thumb is not placed over the top of the grip.