There's an additional pamphlet that came with my Katana MD about re-enforcing the motorbox, including a piece of fiberglass cloth to do that with. I don't recall if the 260 had that as well, as my father built his mostly while I was at work. Other than that, the only changes I needed to make to the original motor box was to drill holes to match the ones in the motor. The holes in the motor box are designed to match the motor PA uses in the IPAs setup, and don't necessarily match the holes on other brands of motor.

At any rate, nothing major.