You have one word wrong, and that has thrown the meaning out of kilter...here's the lyric:

"With Annachie Gordon, I'd beg for my bread
Before that I'd marry Saltoun with gold to my head
With gold to my head and gowns fringed to the knee
O I'll die if I don't get my love, Annachie
And you who are my parents to the church you may me bring
But unto Lord Saltoun, I'll never bear a son
O a son or a daughter, I'll never bow my knee
I'll die if I don't get my love, Annachie"

She is simply describing how she would be decked out in her marriage to the rich Lord Saltoun, with gold ornaments on her head and a gown fringed to the knee, and saying, "I don't want any of that finery. I want only to marry Annachie, and I will die rather than marry Lord Saltoun and bear him an heir."

So, just remove the word "it's" and replace it with the word "with", and the meaning is clear.