Here's a post for Rasimov77 - he shared some goodies in the 'Contributions' section.
Among the links was one for a GUO recording from 1979.
It turned out that it was a part of the recording presented here.
Manfred Schoof, trumpet
Enrico Rava, trumpet
Kenny Wheeler, trumpet
Albert Mangelsdorff, trombone
Paul Rutherford, trombone, euphonium
Günter Christmann, trombone
Steve Lacy, soprano saxophone
Gerd Dudek, soprano & tenor saxophone, flute
Evan Parker, soprano & tenor saxophone
Michel Pilz, bass clarinet
Bob Stewart, tuba
Alexander Von Schlippenbach, piano
J.B. "Buschi" Niebergall, bass
Paul Lovens, drums & percussion
1. Flat Feet (E. Rava) 13:51
2. Reflections (M. Schoof) 12:48
3. Trom-Bone-It [Trombonaut] (G. Christmann) 7:56
1. Boa (A. von Schlippenbach) 11:26
2. Nodagoo (K. Wheeler) 10:47
3. Quasimodo (S. Lacy) 11:23
4. Worms (S. Lacy) 9:53
5. The Forge (A. von Schlippenbach) 9:15
6. Improvisation (Globe Unity Orchestra) (encore) 5:59
Recorded January 26, 1979 at Stadttheater Bad Godesberg, Germany.