Here are a couple of references for collections of broadside ballads. Both of these are at least 8 volumes each. I found them in the library of the University of Oregon, but I'm sure that most university libraries would at least have the Pepys Ballads. Of course they do not provide the tunes. From my understanding the tune was pretty much left up to the singer, whatever fit. I think the ballad hawkers would suggest a tune, usually a popular one that everyone knew, but whatever worked was used.

Chappell, W. ed. 1869. The Roxburghe Ballads. Hertford: Stephen Austin and Sons.

Rollins, Henry Edward, ed. 1929. The Pepys Ballads. Cambridge: Harvard University Press.