You have a good concept, but... Well I suppose I don't need to state it, but, Sephiroth is just not a Naruto character. Simply put, it won't work.
However... If you don't want to make an event based directly around a Naruto character, maybe you can use your own little bit of creativity to come up with somebody who might be acceptable- again, not directly based on or around a Naruto character. For example, you could probably get away with making an event about Bandits from a far-off country. Or a Samurai named Jack? >_>
As far as I understand, that's still acceptable.