The picture of the Nieuport with Esc. C12 that you say you want to do is captioned with a note saying the motor is 160hp, which would certainly be the doubled Gnome. The machine in the picture I posted I am pretty sure is the 'flat front' example, the same as the one in the Albin Denis pictures. Here is another picture, from the front, with some caption information:

The caption information is from 'Flight' in 1914, but I do nt know the isue. It is take from one of the Russian 'pirate' sites.
I found a better example of that drawing:
https://web.archive.org/web/20060217031514/http://mars.ark.com:80/~mdf/N_6d.htmlIt identifies the drawing as depicting the first of three armored Nieuport monoplanes. It seems that in this version, the observer sat under cover, and looked out an opening to starboard. It notes the fuselage was wider than the usual, and this probably continued through the various versions.
The one that actually made it to an escadrille would doubtless be the third, and had a conventional seating arrangement.
The French air service underwent a change in command not long before the war, and the new chief wanted armored aircraft. Manufacturers attempted to oblige, and a number of 'one-offs' resulted. The weight required higher power motors, and so the twin-row Gnome was often featured. It was a wretched engine, mind, very prone to throwing cylinders and needed extensive maintenance. But it was often featured in racers, and also often used in prototypes undergoing trials, as part of the scoring was speed, which when the thing wa working, it could certainly provide by brute force.