I've recently bought a 7-string classical guitar. There are lots of available scores on the Internet for the old Russian tuning. I don't like that tuning very much, because that's a G major tuning, and a bit too hard for my taste.
I've been experimenting with different tunings for a while, and I've stumbled on a modified version of the DAdgad' tuning: it's the G'DAdgad' tuning. It's very nice to have a low G - five steps below drop D! You can play everything that's in G minor very effectively in this tuning, which is very nice, because G keys are problematic in ordinary guitar tunings: the first degree bass is compromised (an octave too high). It's a very nice balanced tuning, too, because you have 2 G strings, 2 A strings and 3 D strings. You must have noticed that A is the dominant and G is the subdominant of D, so you have a very nice, balanced mix of tones and overtones in this case.
Here is my first output for this instrument - Bach's Sarabande BWV 995 in the original key: G minor. It is often transcribed to A minor, especially because lutenists normally have a low A as their lowest string. Theorbo players can play it as it was written originally, because they can go as low as E or D (one octave below our calssical guitar E). I chose this piece, because it's relatively easy for my limited skills on my new instrument. Still, it's quite hard, because decent articulation is very important in this piece.
The transcription is based on two original manuscripts and it follows them in every detail. I've included both modern notation and tab, because I think the 7-string lute tab notation is just right for the 7-string guitar. I've also included some notes after the score.
I hope there are some 7-string players around who can put my transcription to test. I'd appreciate your feedback.