I agree with 2slow2matter, this plane is an ARF and it should be pretty close to balanced when assembled. If you need that much weight in the nose to balance it then something is not right. I would ask what engine you have mounted on the plane. But I would also look at what is making the tail so heavy. Before you go adding weight you need to figure out what is so out of balance. Once all is said and done if you still need to weight then so be it, but I think you can balance without using all that weight.

Hope this helps

Ken