Will check out your Last.FM tag suggestion when I get a chance.
This will help tidy things up, as I expect I have many many songs that are instrumental and have an empty lyrics field.
The makeshift solution I found was through using softpointer Tag&Rename.
It was slow (the program does not keep any index or database, so it had to scan my entire bloated collection), but it got the job done. After scanning, I was able to use its "Find" function, and specify the lyrics field. I was then able to create a playlist from the results, which I then imported into iTunes.
The biggest joy from all this: the realization that with W10, *finally* it is possible to exceed the 256 character filename limit (via group policy or registry). Tag&Rename warned me that I had several violations, and I found out that a solution was finally possible through a google search.