The Orca has worked fine for me, just make sure you put the best armor upgrade you can get on it and make sure the forward cannon is turned off all the time (unless you're fighting a large target that you can shoot down at).
So far I've taken down 5 Osirises with it, so it's not too bad of a ship. Go to Gran Canaria in O49 to get it outfitted well;)
Also, if you want to keep your gunship just put a full missile layout on it:P