After getting side-tracked with my last attempt to "knock-off" this design for the Pattern Review contest I was anxious to try again:
Although the inspiration model as 2 different colors of drapey "insets" in the left side I decided to start with just one. In order to give it more "drape" I used the following pattern idea to cut out the inset (adding seam allowances and markings on the curved edges)
I "slashed-and-spread" on the lighter blue lines which added 4-5 inches to the length of the side seam of the bodice, which would hopefully give it enough "drape".
Here is the result which I'm more satisfied with---I think the "Slash and Spread" is the right way to make an asymmetrical drape