The safe temperature for poultry is 165 degrees.  Keep in mind that with large pieces of protein, there is "carryover" cooking. That means the temperature will continue to rise even though the protein has been removed from the heat source. I highly recommend removing the stuffed turkey breast 5 degrees shy of the safe cooking temperature at 160 degrees so when the temperature continues to rise, it won't go over. The turkey breast should stay at 165 degrees for 15 seconds in order to be considered "safe."