This version of the NLA is often described as not being the NLA at all, but rather the VLCT (Very Large Commercial Transport). It ran concurrently to the 747-X studies. This seems to be the aircraft that Norris and Wagner refer to in Airbus A380, talking about an aircraft being discussed in September 1991 with "four 777-size engines and had a fuselage cross-section of 27 feet, 9 inches, in diameter." (p. 22). This seems to imply a circular cross-section. Reportedly, it was hyped by Richard Bateman, Boeing's Project Strategy Analysis Manager, who tentatively called it the Boeing 787.
Several months later, Boeing VP James Johnson spoke about a 650-680-seater with a circular cross-section, which sounds like the same plane.
I assume that this picture originally came from Flight International, but I found it online. It's crude, but seems to be the NLA/VLCT design in Triton's original post: the door and cockpit configuration is the same. Notably, it also seems to be the aircraft described above: it has 20-abreast seating (12-abreast on the main deck and 8-abreast on the upper deck), exactly as Norris and Wagner described the 9/91 design, and its cross-section is circular. However, the crudity of the image defies further examination: if its scale is correct, then the wingspan is only about 222 feet if the fuselage is 27.75 ft in diameter.
Edit: Note that the upper picture in the image is the DASA A2000, a triple-decker design study from the same time with a similar layout and planform, but an ovoid fuselage.