It is better to go directly to the website of the Bluegrass Messengers. Related materials in other songs are accessed more easily:
www.bluegrassmessengers.com/bluelyrics.html
Messengers

Scroll down on their Bluegrass Lyrics Page to # 3, 'Fiddle Tunes and Instrumental Tune Lyrics'.
One may go directly to this section by using www.bluegrassmessengers/fiddle.html
Fiddle

Scroll down to the versions (10 of them) of Frankie and Johnny.
Much of the material is in Mudcat threads, since the Messengers used to post in them, and used material from them posted by others.

The link posted by Charlie Baum gets directly to "Frankie."

I hope that the Messengers will be able to fill in some of the other categories. Their "Fiddle Tunes ..." category is very helpful.