First you would need to save out a copy of the old part in another directory or even a portable drive. If the old part and the new part isn't hard to reproduce, why not make the changes to the old part first, like you want the new part and then change the name.
I think I had one of those "DOH!" moments there. Not sure why I didn't think of that; we've been using EPDM for like 5 years now. Anyway, that's an easier approach than what I was thinking.
Thanks for your help,