An old friend of mine, Hank Harris, has released a CD called the Deadwood Songbook. It was partly sponsored by the South Dakota Arts Council, the Adams Museum, and Deadwood itself. No doubt the popularity of HBO's "Deadwood" was a factor.
It's composed of the standards of music in Deadwood's dancehalls from the 1880's. Effort has been made to retain the instrumentation and feel of the times.
What may be of interest is that he has a very nice instrumental version of the "Gary Owen".