cut a new w1 rib about twice as thick as the original, glue to one wing half, now you can sand a wedge shape to the desired dihedral angle, make a new dihedral brace from the plans and join the wing halves. Go flying, have fun. I have made the same fuse side before, joined the wing upside down, made a banana fuselage once. you build long enough and you will make all the mistakes at least once!