I'm working up an early dh.86 express. Still some months from completion, but at least now I am reasonably confident I can see it through.

Lee Holmes was kind enough to send me his fsds source files, which have proved an excellent starting point. I'm doing the prototype with the pilot/radio operator layout because I love
its look and I think the pilot's viewpoint is much better suited to a v.c. than in the dual control model. That still gives us two R.A.S. aircraft and the Imperial Airways Delphinus.
This is my first fsds project, and I am still on the learning curve. I would imagine I'll be back on your forum from time when I get stuck.
I'm working from the 3-view of the prototype and rather copious documentation in the online flight magazine archive. The three view had a rather large amount of distortion from being squashed onto the scanning platen. Got rid of most of it in Photoshop. The Flight 3-view is still wrong about the tail, but fortunately Lee Holmes nailed it, so nothing for me to do there.
Sadly, Graham Simons book on the Express is out of print and I cannot find a copy. If Mr. Simons is about, perhaps I could ask him for advice as I blunder along?