Welcome to the world of 64's. We are kind of the Ba---- child of the Chevelle world. There are things that are reproduced for every other year that may not be reproduced for 64. The first question is which side do you need? Second, are they so bad that they must be replaced, or were you thinking that it might just be easier to replace them than repair them. While they were manufactured as a seperate piece from the front fender, they were welded to the fender during construction. So, if it's not that bad, you might want to repair what you have.
One more thing, it helps if you add to your profile, so we know where you are located. There are many guys on this site that are able to assist locally, as long as they know where you are.