Dale,
I echo everyone else's remarks, and then some, this is some of the best model engineering work I've seen lately, but, (and here it comes, if you haven't heard it already) as beautiful as those wheels are, if this is to be a working locomotive as opposed to a glass case model (which it qualifies for so far) sooner or later it's going to need steel tires. The question would be when to do that; now, when it's relatively simple and quick, or later, when it's not. I also recognize you may have taken this into consideration already and what you've done suits your needs. The casting work is indeed beautiful.
PS - If you would take the time, a description of your pattern making and casting process would be very interesting.