Thanks for the feedback!
It was very tricky to make any sense of the drawing and I may well have been chasing a red herring, but it appeared there were multiple small apertures around the cockpit area, rather than large glazed areas, as often portrayed in post-war drawings such as the one at the top of this thread. This does make sense, as the P 122 was supposed to be pressured and able to operate at extreme altitude. The only things that came close in WW2 Germany were the Hs 130 and DFS 228. Neither has large glazed areas. This reminded me of today's White Knight One and Space Ship One. So I went for that bug eye cockpit glazing style, tracing any lines I could discover in the drawing.
Marat's model is very nice indeed and this cockpit arrangement might have been possible too. Perhaps with extra bracing, like on the Bell X-1. A layout similar to the B-29 is also a possibility, but I doubt the Ar 234 C style we normally see on drawings would be feasible at 40,000 ft.
About the landing gear and bomb bay... In the original drawing there seem to be traces of a bomb bay in front of and behind where the landing gear would be. But it's possible the entire bomb load was to be carried on the wings instead - no doubt some sort of smart bomb, as Henschel was a pioneer in the research on these as well as high-altitude flight. The P 122 was no doubt to combine the results of both.
My older Henschel P 122 reconstructions can be found on my website, here: http://digitalaviationart.com/skyraider3d/hsp122_2.htm
Cockpit design was an earlier interpretation, a band-aid style design by the suggestion of Thomas Hitchcock (Monogram publications) who also didn't believe in large glazed areas being possible yet in 1945. It was for Monogram that I first designed this 3D model back in 2003 and it features in Manfred Griehl's secret jet aircraft book, vol.2. In my old artwork it doesn't have any bomb bay for reasons mentioned above. Plus I could barely fit the main wheels and simply wasn't sure where to put the bomb bay next! I went with an Me 262 style gear then, but if I'd rework it today I would've gone for an airliner style with multiple smaller wheels on a single axis. Either way it would be great if a clearer wartime copy of the P 122 surfaces one day. Until then the cockpit, gear and bomb bay arrangement will remain an educated guess at best.