Just remember to keep your geometry the same. The width of the servo arm should be the same width as the control arm.
Also, keep the control arm on the rudder either flush with the hinge line or slightly behind (1/32-1/16") Keeping the control horn slightly behind the hinge line will cause whats called reverse akerman. In other words, at full deflection one of the cables will go slightly limp which is OK. If the control horn is in front of the hinge line then you will have problems with binding. Not good.

What kind of control horns will you be using?
EDIT: Not sure how that smiley got in there. Can't seem to edit it out.