The old one was rejected 5 years ago and I think a fresh PEP is fine. It makes it clearer to see what has changed since then, and we can leave the old one as a historical document with its historical rejection notice. Also, each PEP has a different pair of authors.
We can however add “Replaces: 601” to the new PEP and “Superseded-By: 765” in the new one to show their relation.