>Verse 34 as given could be compared to the last verse of a ballad collected in Dumfrieshire by Burns

Also to verse 5 of "Young Bekie" (Child 53C):

Or gin a virgin woud borrow me,
I woud wed her wi a ring;
I'd gi her ha's, I'd gie her bowers,
The bonny towrs o Linne.

(That was certainly available in print by the time of Buchan's MS, in Jamieson's Popular Ballads and Songs, 1806.)