The fact that you stipulated that the CR.42 DB be given a couple extra machine gun pods indicates you know what's wrong with the idea. According to wikipedia, this plane had a speed of 326 m.p.h., which was still slower than a Hurricane II, and the weight of the gun pods would have reduced its speed to slower than that. Increased speeds dictated that combat planes would have themselves in each other's sights a reduced amount of time, meaning more guns were essential. Even during the Battle of Britain, the Spitfire and Hurricane really should have had more firepower than eight x .303-caliber Brownings, their German rival the Me-109E with its 20-mm. cannon showed the way ahead.