don't know how good you are at altering patterns, but this dress has a similar collar and I "think" could easily be made just into a loose-flowing top:
http://mccallpattern.mccall.com/m631...hp?page_id=486
Collar's similar, but shirt is gathered at bust line:
http://mccallpattern.mccall.com/m579...hp?page_id=486