Halvorsen wrote a very popular Passacaglia on a theme from Handel for a violin and viola duet. Lesser-known is his Sarabande and Variations on a theme from Handel, also in G minor and a duet for violin and viola, although I think it is of at least equal musical merit. The Passacaglia is already on IMSLP, and both pieces were composed in 1897, according to Wikipedia, so I think there should be no issues with copyright. I would greatly appreciate if someone with access to the score could scan and share it, and I am sure the musical community would be very thankful as well.
Kindest regards.
Handel-Halvorsen Sarabande con Variazioni
Actually Halvorsen's passicaglia is just a transciption of Handel's piece, though it's not here (http://imslp.org/wiki/Suite_No.7_in_G_m ... rideric%29)