I saw that frame and you got a nice deal. I would think a 15 would be a good option. You don't want a drop in bobbin for sure as you will really be unhappy when you have to deal with the quilt on top of the bed every bobbin change. I wonder if a larger throat industrial would work or if it would just be too heavy for the wheels? I had a 301 on a frame for about two seconds and it was just too tiny.