Usually having the wider top and bottom gives the top a nicer framed look. Are you going to have to piece the top and bottom? If so, it would be advisable to piece it directly in the middle to continue your plan of having the seams follow the seams on the cats. This would tend to make them all blend into the quilt rather than stand out. Love the cats (my daughter has been asking for a cat throw). I think it has just enough 'wild' print to make it pop.