I like your idea of keeping what you have for a bean only planter. Then add a newer 30" planter for corn. You're far enough north where narrow row beans are worth it so....keep those. If you go to a 1770 NT you can eventually put PP or Deere electric meters on it. It will likely come already with clutches (if you get one with row command) so you'll do far better than the sections you have now.