Bruce,
You are quire correct.There is no readily identifiable comparison, tune wise, between The Unfortunate Rake and The Dyin' Crapshooters Blues. As with many people I know who can't read a note of music and has no formal education in music theory I tend to use "tune" and "song" interchangibly. I know I shouldn't. The comparision I draw between the two songs is lyric. In one version of The Troopper, Soldier, Sailor, Unfortunate Rake, Cut Down in His Prime the dying man asks for Six flash girls to pull my coffin. The Dyin' Crapshooter in one version I've heard he wants wants Faro Dealers for pall bearers and hookers to sing one last song. The Unfortunate Rake is dying from what is definately Vernereal Disease, " .. I might have bought salts and pills of white mercury.." The Dying Crapshooter tells his friends he lived a squallid life and evil ways have killed him. I believe this refers to more than drink. Both songs refere to the smell of roses as preferential to the smell of death. With so many versions to reference the lyrics from we can make alot of perhaps unscholarly, but certainly legitimate comparisons for the song if not the melody.
This discussion may be proof that the variation in song dispersal on two continents is at best only beginning to be studied and much more work in the area of folkmusicology is needed. Sounds like a fun project for when I retire:-).
Warmest regards
Don Meixner