Refasionista

I saw this dress in a charity shop a couple of weeks ago - when it was still there today I decided to buy it. (I have a tendency towards procrastination - should have bought it when I first saw it.) It's a Wallis silk dress - UK14 - looks rather like a sack - but I love the fabric and the colour. I'm now trying to think about how I'm going to refashion it. As it's only a couple of sizes too big, there's not enough fabric for a complete remake. It needs to be an adaptation. I'm thinking along the lines of a shift, no sleeves and slightly more fitted. I don't have any suitable patterns, so I'll need to draft something or pin and stitch as I go.
I'm going out with my mum and sister soon and would like to use this dress. I suppose it depends how successful it is. Any suggestions gratefully appreciated.