I'm afraid on the whole the only people with literacy showing any interest were the antiquarians. Unfortunately they were also poets by and large and couldn't resist tampering and imitating. As I said there are no shortcuts I know of. Get in there and sift. We've probably covered the obvious exceptions in Huntington, Thomson etc.

Another possible source where you will find very relevant material is the JAFL and similar regional publications.

People like Norm Cohen, Ed Cray, John Grant and Jonathan have already done a lot of the groundwork. You could save yourself a lot of time by consulting them.