I would recommend getting a set of sights for the gun.....you can always take them off if you want to use it for something else later on.
While you are patterning you will notice quite a few different shells will not pattern the same, and that is when you will want to be using adjustable sights.
Once you decide what gun you are going to get just let me know and I should be able to point you in the direction of a couple of good shell/choke combos.
Welcome to the addiction of turkey hunting!