I'm roasting boneless pork shoulder today. My butcher took the bone off, so I have two big pieces, around 3.5 lb each. I normally roast pork in the oven (300 F), for around 40 minutes per pound. This is my pickle? Since I'm cooking the pieces in the same roasting time and at the same time, do I calculate the roasting time for 3.5 lb or for 7 lb?