Why would you need to finish the ribs in the oven? Cant u cook it all at the same time? Do a hot n fast at 300 and u will do just fine. throw the chicken on 2 hrs prior to the ribs being done and u should be set. you can also crisp up the skin by taking the chicken right on the grate, remove the middle section and put the grate on the fire. just be careful because u can burn it.
Weber Genesis Silver B, Twin 18.5" WSMs, Weber Performer, Green Weber Smokey Joe Gold