Enoch Powell dying sometime before his "Rivers of Blood" speech would do him wonders.
Outside of Tory circles he was effectively a nobody before Rivers of Blood. If he dies before then then he's going to be remembered on practically the same level as Geoffrey Rippon or Peter Thorneycroft. Rivers of Blood, and everything Powell did after then, sharply polarised opinion on him but I don't think you can say it actually diminished his reputation, because he didn't really have one.