The scholarship displayed here is nothing less than frightening (I would have said "sobering", but that wouldna been appropriate).
Haven't heard the Barra McNeils' version as yet, but there's a lovely rendition by Bobby Watt on his "Homeland" CD - not the conventional melody.
As for the line:
"We'll tak'a richt gude willie waught ..."
My notes translate "gude willie waught" as "good will/draft of ale"