I converted a Harpy a while before the proper Flyrant model was released. It used the plastic Balrog wings you can buy as bitz from the
GW website or ebay, and the body of a 3rd-edition Hive Tyrant which has a long flowing tail with just the right shape. The head is from a 3rd-ed Zoanthrope, and it capped off with some spare
HVC's. It worked out way cheaper than buying Trygon and
HT kits to mix up.
I don't have a solo picture of the model, but it's in these full army shots if you zoom in (in front of the Zoanthropes):