2-56 hardware is plenty for a 40 size plane, as a matter of fact I remember my old four star 60 kit coming with 2-56. Maybe the rods were soft? All 60 size pattern planes used 2-56. 4-40 is only required for IMAA. In the first post the photos showed the links too far in on the horns and I bet there was no machanical advantage. That will cause flutter.

I like the mass balancers.