Think about where the parts attach in final assembly. The hinges must connect to brackets on the wing. The spacing of the brackets is critical. When you mount the flaperons the hinges must be centered in the slots on the flaperon. This may require that your wing mounted brackets be shifted very small amounts inboard or outboard to keep them even. Especially, if the spacing on your ribs was not absolutely accurate when you built the wings. The innermost hinge is the only one not attached to the flaperon by the factory. It is the only hinge that you can adjust the spacing. Make sure that hinge will align with the bracket on the number one rib.
The control horn connects to the flaperon push rod. The control horn hangs out in space under the turtle deck. It can be off by quite a bit and still clear the fuselage. It is not as critical in the inboard to outboard spacing.
I have all my rib dead center per drawing, was not sure on the 5 1/4", I know it floats inside the deck but was not sure how much angle was built into the tierod fitting allow. Thanks