The only time we had a moth problem, they ate holes in my two cashmere sweaters. Snobby moths, I guess, because they left the wool alone, LOL. I bought those cedar pieces they sell in various catalogues, and haven't had a problem since.
Since this is a special quilt, I might go with Quilter's Dream Request cotton batting, which is specially made for hand quilting and which people rave about, just so as to not be worrying about the wool.