R-2800 do not give you enough power to do that, even if you strip plane from all armor, weapons and most of fuel. Maybe in hard dive but never in straight flight. If "standard" F8F reach 840 km/h why they all not fly with 800-830 km/h speed ? Data say the max speed of serial build F8F was 740 km/h.
He said
one standard Bearcat.
I'm personally willing to bet that said 'standard' Bearcat was about as 'standard' as a mechanic friend of mine's 'standard' Volkswagen Jetta. Yes- everything under the hood says WV, but that doesn't mean that every moving part hasn't been timed to the nanosecond, injectors tweaked and altered ever so slightly, fuel/air mixes optimized and everything is hooked up to a computer once a week for some obligatory "what would this do" alterations.
These machines were the only things between their pilots and a horrible death- and their crew chiefs knew it. I doubt very seriously that fine-tuning to the point of insanity didn't occasionally occur with a good ground crew.
My M9 Beretta looked 'stock' - but when I left the Guard, the trigger spring and captured recoil spring that I put in went home with me... not to mention my personal mags (cause Army mags suck).
Few people in the military trust something at stock specs with their lives- we tinker with everything.