"One of his assassins was identified as having distinctive red hair"
I seem to remember that was 'Rory' - name fits the colour.
"....every man had shaved off his hair."
Latter day Croppies!
There's an excellent little booklet (134 pages) entitled the Third Earl of Leitrim by local (Donegal) man Liam Dolan (1978) which may still be floating around - we used to have two copies but gave one away, otherwise you would have been welcome to it.
We do have an article about the Ballad by AL Lloyd, and numerous other bits and pieces, which you are welcome to copies of - if so, PM me.
Jim Carroll