Yeah...
Looking at this again, it seems that it's not the ball that's off so much as the wing post thickness and length, the height of the center section of the wings and the angle of attack of the wings' bends.
I'll bet that if the wings could be reworked, and the modification to the wing supports I suggested earlier were done, then the Kelley would be a lot closer.
A lot of work either way. But I think doable for one with lots of time and patience.