I do not know if it can be turned into a 22 hornet gun or not. But, is it worth it? It may, or may not be. 22 hornet can be pricey ammo, while .22lr is not and you could shoot a 1000 rounds for 14 buck, vs. 20+ dollars a box for 22 hornet. 22 hornet is also center fire, so it might take alot more then first thought to change it over, Im really not sure.
What is it you really want to do with the rifle? If it is pinking and small game you want, stay .22lr. From what Ive hurd "as is" there a pretty good shooting .22lr gun. IMHO if I had one I would leave it "as is".
Dave.