There is an older, pre-baroque, tuning which is, starting from the bass and going up:

G as in the 3rd fret of the bass E guitar string. The other one in the pair is tuned an octave higher
C (a fourth above the above). The other in the pair is an octave higher
F and the other one in the pair an octave higher
A and the other one is at the same pitch
D and the other one is at the same pitch
G and the other one is at the same pitch

The seventh string (or pair) is/are tuned either a note below or a fourth below the low G.

This was used (I think) into the 16th century; but changed before Weiss.

You might also try the newsgroup

rec.music.guitar.classical.guitar

and

rec.music.makers.builders

The former has some lutenists hanging around on it, and I have gotten some questions answered about tuning there.

Murray