Geame. Something does not seem to tie up. The following photograph was taken from a Tupolev ANT6/TB-3, which ties up with your earlier cutaway drawing.
You say that the challenge photograph is identified as the ANT6/TB-3 I would love to know what version. Looking at the photograph it looks as though the cockpit is located off centre also there is no sign of the corrugated skin as shown in the photograph above. Interesting.