The dress is in the movie for such a short time (which is a total shame since it's the best dress she wears all movie long) I don't think it really matters even if there is/maybe/could be a slight difference in hue.
You did a FANTASTIC job on it. I think it looks spot-on! :D
I had a really rough time picking the color of her dress. The pictures aren't that great of it, seeing as it's sort of a sunset-scene, and it's also a VHS movie. But I picked this one. It's periwinkle, as far as my eyes are concerned.
Thank you, Fiona!