If you don't mind the cost, new longcase clock bells are available in various sizes from horological parts suppliers, they come in various sizes in the correct metal with a nice ring to them.
They can sometimes be purchased quite cheaply in salerooms on old movements.
http://www.m-p.co.uk/muk/parts/chap0...0280043815.htm
http://www.m-p.co.uk/muk/parts/chap0...0280051215.htm