Just checked some of them in Digitrad. Careless Love is there, but it's not a version I know and certainly not the one done by C&W and JW. Frankie and Johnnie is there, as is Casey Jones. Couldn't find CC Rider (it's sometimes known as See See Rider or Easy Rider, but they didn't show up either in my cursory search), but lots of other songs did that have been recorded by the likes of Mississippi John Hurt, Mance Lipscombe and lots of others. You might also check out a lot of gospel tunes, which lend themselves to bluesy arrangements. You might also consider a lot of train songs (Eliz. Cotton's Freight Train springs to mind) and any of the dozens of versions of Titanic — if that hasn't been done to death because of that god-awful movie.

good pickin',

david