Guitar Tab is a popular term; but you will need to develop it a little to get results. It could then be a really good saleable name.
At least GuitarTab does go with the .nfo extension
You see a lot of names that don't suit info at all.
Make a useful guitar tab site and it should appear in search engines (even without "listing" it these days). Never heard that .info has a "ranking issue"; just more developed sites exist under .com, .net, .org etc.