Very few folks can do this work profitably. We (my brother, who is a machinist and not a railfan) couldn't keep the lights on. Joe Foehrkolb realized that there was more to life than working your tail off for not very much money. Jay C may still be doing some 2-railing.
But good brass Williams is not that big a problem. Sell your 3-rail, and buy a 2-rail version. I have a factory 2-rail "J" and Mikado. I may someday sell the Mikado, but it is a nice model. I have seen 2-rail N&W Class A and SP Cab Forwards. I am sure there are others.
I am not automated. It takes me around an hour to insulate one drive wheel, and at sixty bucks an hour, nobody will hire me. That's the way I like it!