I think you need to allow 3 bones per adult person, then allow for 1/4 lb cooked meat of the other choices. Folks are going to want the ribs first. I also second putting the ribs at the end, or close to the end, so that plates have food on them before folks get to the ribs. Sauce on a separate table is best. Or have them at each table.
I'm feeling bearish, and I'm packing a Wusthof Grand Brisket slicer from MABA
"perhaps...but then again...maybe not..."