Well as far as I know you're both right. The Corsair was designed for a telescopic sight that was going to be the USN standard, but the US was allowed to license the British Mk.II sight from Barr and Stroud. So the "guts" of the N-series sights, as well as the USN Mk.VIII, and Mk.IX sights are all the same. The USN adopted the N-3 for a short time until the development of the Mk.VIII was complete. This is discussed in the book of the joint fighter conference, at NAS Pax River in Oct 1944.
So given that the F4U-1 in game seems to me to be a later production model, I suspect the Mk.VIII is more correct, but it could be either.