It's very easy to make a top down sweater larger, you just keep knitting the increase rounds until it does fit.
There's a topdown raglan pattern generator at the Knitting Fool
site. You put in your gauge and the measurement you want and it makes a pattern for you. If you like the look of this tunic, use a measurement a couple inches smaller than you are, and knit the length from the underams to the hem longer, maybe use the length given in the Ellie sweater.