The Navy played fast and loose with some of those specifications.
We can find documents that claim 13.5 ultimate load factor (9G service load?) for the Hellcat too, so the same for the F4U is certainly believable on that score.
Unfortunately the F6F is for a "designed" weight of 11,000lbs and the chances of any F6F operating anywhere near 11,000lbs (unless at the end of a ferry flight or about to land on the carrier running on fumes) is pretty low.
example of fast and loose is an early Spec for an F4U-1 in "standard" configuration and in "Overload"
Standard was 11,142lbs while overload was 12,656lbs.
Standard only included 178 gallons of fuel and 1200rounds of ammo (200rpg) and I doubt very many were ever flown that way, at least at the start of a mission.
Overload was 2350r rounds of ammo (about 344lbs more ammo) and 363 gallons of fuel (outer wing tanks full. no drop tanks)
So one can see that the 13.5 load factor (9 G service) was something of an illusion. Full internal fuel and full ammo would bring the Service load down to about 7.9 which is still very strong.