To increase the throw of a control surface you put the pushrod in the outside hole of the servo arm. At the control horn on the aileron put the pushrod on the closet hole to the control surface. This geometry should give you more than enough throw. You shouldn't need to make (not to mention the problems with even trying) to make your own servo arms. See included diagram

Turning the clevis in or out is not used to adjust the throw of the control surface. The clevis is used to adjust the center position of your control surface.

Hope this helps

Ken