I love this song, have known it and its lyrics since 1967 and am currently practicing it for a 20th or so year to get it just right in a new version with minor modifications of melody to play at my local sessiun.

Frank Harte's song and lyrics books has it and a similar wondrous little tune, "The Ragman's Ball." If I had the book handy I'd read you any differences in Frank's version, such as "any Midge" which I've sung for years. I know Frank was mentioned in another message and he has a good handle on the old Dublin tunes. I wonder why there is doubt as to a Zosimus ascription? Also, I believe the Dubliners say "billy cart," despite the lyrics. Too, on the Zosimus ascription - if one can attribute the Ragman's Ball to Zosimus, it is difficult to divorce that melody from the Twang Man. They sound like they had similar authors or background somehow, although, they both could be non-Zosimistic in origin.
Best to all
John