I had the same nose-over problem with a Great Planes Corsair .40 that I built, and nearly everytime, I banged up the rudder.

I solved the nose-over problem by bending the (fixed) wire main gear forward of the leading edge about 3/4", but not before i built a whole new vertical stabilizer and rudder out of bala WITH 1/32" ply glued to each side of both. Never had broken rudder / vertical stab problems again.

Mike