The two dictators can't be any more different in terms of legacy. Though extremely bombastic and lacking a good deal of the advantages Germany had, Mussolini played his cards extremely well. He managed to overturn what a lot of nationalists thought of as la vittoria mutilata, revitalized and industrialized a primarily agricultural state, solidified an empire in Africa, and through diplomacy and subterfuge managed to break British Hegemony in the Mediterranean with a new Alliance. An impressive record honestly.
Then you have Hitler. After managing to militarize the Rhineland and kicking his country's struggling economy into high gear, he horrendously mucks up Anschluss, nearly went to war with France over the incident, and manages to get his army's ass kicked by poor and modernizing Poland when he horrendously misjudges the attitudes of the Little Entente. If Poland didn't win so quickly; it's said his economy would've collapsed after cooking itself to death.
I really am curious on how you can reverse these two's legacies honestly, since it doesn't seem to be as ridiculous as say keeping the Third Republic stable, or having Japan actually win against the Soviets.