The record including "Railroad Blues" Art refers to, produced by Mike Seeger, is called "Old-Timers of the Grand Ole Opry"; it features Sam & Kirk McGee & Fiddlin' Arthur Smith (Sam + Kirk = Uncle Dave Macon's Fruit Jar Drinkers), and is on Folkways. There was a second album, "Milk 'Em in the Evening Blues", just as good. These are overdue for reissue on Smithsonian/Folkways, but meanwhile you can get 'em as CD-R recordings or cassettes. (Be prepared to wait 6 months or so -- they're badly backordered at Smithsonian/Folkways.)
Peace. Paul