We cook our chicken from frozen @ 275ºF for approximately 1 hr. per pound, checking with a meat thermometer for proper doneness.
If you wish to stuff the chicken, still cook it slowly at a low temperature of 275-300ºF, and again check with a meat thermometer for the proper doneness.
Remember that these chickens have had a life of roaming around outside and therefore have muscle tissue, rather than conventional chickens that never see the light of day let alone are allowed to wander. Therefore the meat is more nutritious and tastier however, it also must be cooked accordingly, slowly at a low temperature to achieve tenderness.