Davie Stewart is worth checking in this context, especially his preamble on the Lomax CD which gives the whole thing an air of authenticity. Either way, his rendering, I'd say, is pretty damn definitive. In The Reader's Digest of British Folklore & Customs you can see a picture of the MacPherson's broken fiddle, but I can't remember where it resides.

Rant or Fairwell? Again, I defer to the great Davie Stewart on this one!