The Italians did fit a DB601 engine in a CR42 giving it a top speed of 320+mph. Uncharactoristicaly sensibly they didn't put it into production, leaving their limited allocation of German 601 engines for their monoplane fighters.
A 601 engined Avia B.534 for East European Allies of Germany might have been possible, and could have done reasonably well against the Soviets for the first year or two. Even later it could have been used protecting the supply lines from partizans.