The top wing's shading is very incomplete as of now (and so is the lower wing in fact). As for what I'm working from, I'm not sure what you mean.
I started with a not-too-bad line-view drawing of the SV.4A which has been corrected extensively using pictures of the bird (you can find some on airliners.net also by searching F-BCXD). I also have walkarounds of other sister Stampes.
The owner has just mailed me further mods he wants carried out: a change in the rudder's shape, more slope on the engine cowling and a few other minor changes. I don't agree with all of those, but he knows the plane better than I do, and he's the "end customer" anyway. Even though I'm just being paid in beer and airplane rides

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Here is a lo-quality pic of it:
Mail me if you want a zip with all the material I have.