Don't know if it's of any help, but I was told of a 'reverse' musical journey back in the 1960s, when the great Scottish ballad singer Jeannie Robertson changed her tune for Musgrave/Mattie Groves to one she learned from the American singer Sandy Paton when he was at a festival in Aberdeen. (I used to think it was Jean Ritchie from which she 'borrowed' it, but have been corrected since.)
If you can access a version from Sandy Paton, you can compare it with several versions from Jeannie on the Kist o Riches site (archive of the School of Scottish Studies in Edinburgh) -- just search either song title or singer.