Your battery should weight ABOUT 5 oz and you moved it to the rear only 2". Then, to compensate, you put a whole 3 oz of lead in the front. I think you moved the CG ALOT to the front and in bonus, you got a heavier plane.

I have a scratch built CAP 232 at 11 lbs with the same wing area as yours and it is not eccessively heavy. In fact, it flies quite good. At least good enough for 2nd place overall in advanced NE region IMAC.

IMO 10.5 lbs is perfect for this size and you more likely have a CG problem than a weight problem.