Charlie, Floquil makes a color called "Old Silver", which you can mix with either flat or gloss coat, or 50/50 for semi gloss. I had a friend use it on a Burlington 44 tonner, and it came out really well.
Steve, is that a William Crooks repainted? I have a customer that has one with a broken roof support, it is a wind up and is OK otherwise. It has the tin tender in good shape, but your repaint makes me brave enough to tackle it.