I've seen data for the Fireball, and while it was generally inferior to the late-war fighters up high (such as the F4U-4, F8F-1 and F7F-2N), it was plenty fast down low. As much as 399 mph at sea level, but not much faster at 426 mph up at 18,100 feet. Climb was excellent down low, with an initial climb rate of 4,800 fpm from sea level. Climb fell off some above 12,000 feet and it required 5.6 minutes to get to 20,000 feet, which means it averaged just under 3,600 fpm over the 20k climb. Not bad... Better than the F6F-5 or Sp-51D.
Wing loading was pretty darn good at 36.2 lb per sq/ft at normal takeoff weight. The Fireball was also fitted with a laminar flow wing design. Navy tests showed that it was highly maneverable, fitting in between the FM-2 and F6F in turning ability. Pilots who had the chance to fly the Fireball, liked it very much. It did remarkably well in its carrier quals.
Overall, it would be a monster in the game, where most combat is at low level. It would turn better than the F6F-5, Climb better than an F4U-4 and run down a Tempest in short order. It would be a beastie. Its only real weakness is FM-2 quality guns.
Unfortunately, the first operational squadron was still not yet been released for combat when Japan surrendered. Therefore, we will never see it in the game.
My regards,
Widewing