http://www.trackofthewolf.com/categories/tableList.aspx?catID=14&subID=142&styleID= 491 Here are some good choices. You might have to modify the thimble rib slightly to make them fit. Green Mountain Barrel Co or TOTW can tell you how. Then again, like me, you might not have to modify them at all.
That is a nice looking rifle there Roundball. It is one of my favorites!!!