Are you brining the breasts? That can affect cooking times. And, what temp do you want to cook the lamb to? IT 135°, 145°, 155°, or 165°? The turkey should be cooked to min. 165°. And, do you have an approx. physical size or Qview? And, what ext. temp your smoker? I would guess around 3 hrs. myself, but with no visual, or temp, it would be hard to guesstimate. Also, you want to put the lamb above the poultry otherwise drip contamination from the poultry.