Wish I'd noticed this thread a week earlier--Avro, I'm a big believer in having as much knowledge about the shape of a thing as possible when building it; and, just for starters, there's no similarity between the Emil contours and the Gustav's (the F was transitional and we can treat that separately)--it's more than just the E hump and the G spinner, the outlines are different and it's subtle, but if you get it, it's significant and a huge bit of the character of the planes.
This might benefit from a good ol' basic sectional paste-up and skinning, just to see the differences in how it'll unfold from what FG has got so far. (Not many people notice, for that matter, that the planes' noses are also non-symmetrical in section, but that's getting pretty geeky!)
It may help you a lot to have good drawings to work from. I've got the very good lofts from the British Museum, and I could scan 'em if you want to get that deep into it--got a couple other good sources but I'd have to do some memory-refreshing, it's been a couple decades. Write me at hudsonduster[at]hotmail.com if you like.