Basically though, having a separate model for the F2A-3 would satisfy all three: US, Commonwealth, and Dutch.
Not really. The F2A-3 was substantially different from the B-339. It had far greater fuel capacity and the fuselage elongated forward of the wing to offset the CG shift. It was also powered by a 1,200 hp engine and about 15 mph faster than the B-339s.
The B-339 was based upon the F2A-2, or should I say that they had a common root.
In theory, the weight of the B-239 could be jacked up to simulate the B-339. However, the F2A-3/B-439 would require increasing weight, fuel capacity (this Brewster had greater range on internal fuel than the long-legged A6M2) and power. Technically, the model would require stretching the fuselage (8").
My regards,
Widewing