First, let me assure you that despite my comments this is much, much better than no F2A-3 at all. And my own skills in this respect are absolutely nil, otherwise I would have started work on converting the F2A-2 into an F2A-3 ages ago (not to mention making the B-339C and D, the most important versions). I wouldn't even know in which SFS file the required F2A-2 files are located! Ditto for the Buffalo Mk.I which would be the basis for the -B, C, D, SSSS, PRU, Nightfighter and the longnose 339-23 versions.
Strange that the B-239 skins work but the F2A-2 skins don't when both modded versions have the same longer nose, though. But perhaps it might eventually be worth having special skins made for a “correct” F2A-3. And a Buff Mk.I modded into a 339-23 would probably have the same skin problem that your modded F2A-2 has.
The only other comments I have re your model concern the framing of the sliding canopy and the barrels of the 20m guns. Re the latter, perhaps the Hurricane IIC barrels might be better?