I am doing the same in my kitchen and breakfast area. I just finished laying white pine on the floors and have some extra T&G yellow that I am going to put on the ceiling. How are you going to finish and seal your ceiling and are you going to put any type of moisture barrier on the joists before putting up your wood? I am facing these delimas now and am planning to start this weekend. In answer to your question, depending on what spacing you have on your ceiling joists, some cutting is going to have to be made to fit them on centers. From experience, I would highly recommend you square off the ends of the boards before fitting them together. I found that alot of the ends were not real square from the mill. Hope this helps!