He did not fly a Type N in combat, Sir.
The armed machine he flew was a Type L parasol. There are a couple of pictures of it, and it had no particular markings, aside from ordinary service markings, and the usual black trim of Morane-Saulnier.
Before the war, in a racing meet at Aspern, Austria, he flew a machine designated Type N. This differed considerably from the eventual production 'Type N
militaire which your picture illustrates. It had a circular section fuselage with a projecting headrest (on the production version, the headrest was faired into the fuselage, giving it a pear-shaped section).
Its appearance was very similar to this (my early scratch-build of the prototype Type N
militaire flown by Gilbert:


Of course, the pre-war racer did not have a gun.
The windsock Datafiles on the Morane-Saulnier Type L Parasol, and on the TYpes N, I, and V monoplanes, have solid information and photographs on this.