A flying buddy managed to put the wing joiner in upside down in a Lanier Mariner 40 seaplane resulting in anhedral. The plane only had a slight dihedral designed in originally. The bottom line is the plane flew fine but needed some upthrust put into the engine. The only downside there is that if the power was cut abruptly the plane tended to sink a little quickly.

Either get out the razor saw, order a new wing or just give it a shot to see how she handles.

Good luck!