the glazed nose and proper gondola are the major things. oh, and the interior stuff specific to the glazed nose
do you have a gondola with a bomb sight in the front in addition to the cannon armed gondola of the C-6, and the interior parts for the nose?
If not, I am (someday) converting a Dragon A-4 to an S-1, and therefor have the gondola as a spare. I'm more than willing to send it along.
As for the interior pieces for the bombardier position, well, those could be easily scratch built. In fact, I may have to if my research shows the S and A differed in this area...