The "Traditional Ballad Index" is among the links provided by the green "Links" at the top of the page (I don't know why Mudcat has "The" attached to some of the sites- most listings avoid this). Their format is good and seems to provide the info you want.
For a number of the songs, the information in Mudcat is more complete than that in the Index, if sometimes difficult to find. Nothing is more frustrating that to put in the title of a song version and come up blank even though, when you finally find it in the DT, it has the same title as the one you put into DT- example, Harry Jackson's version of Streets of Laredo). I would guess, however, that you want to provide as well for non-trad composed songs that are played by "folk" musicians.
It seems to me that there are already a number of indices, admittedly not perfect, and I rather hate to see more. Perhaps a compromise would be to have your index, but linked to the other major listings. A good deal of anything started from scratch would be duplication of other resources, and by linking to pertinent information already out there, much of this would be avoided.