Like FLBR said, Chicken on the bottom rack will work at 240 to 250.
Skip a rack then the ribs on 3rd rack.
put a catch pan under the vent on the top rack in case you get alot of moisture from the chicken.
Since they are BB's 2 hrs of smoke should be plenty and that will work for the chicken also.
Keep the vent wide open.
After the chicken is done, you could lower the ribs a rack down.
Just besure and monitor the temp under the lowest rack of product.