I'm going to have to say that I agree with humble on this. The only thing I'd disagree with is the time it takes the P51 to get an E-advantage. IMO, he can do it very quickly in an "equal" start 1 on 1, with the time and space he needs to handle the fight.
All the P51 needs to do is set up the merge to "lose", which will cause a huge percentage of F4U pilots to be predictable and scrub E for position. By that, I mean if the P51 dives for speed in the "normal" merge we all do so often, and "accidentally" allows the F4U to pass slightly under the P51, the F4U will almost definitely pull an immelmann, and probably a pretty hard one at that. The harder the F4U pulls, the more E he scrubs, and the closer to black-out he gets, which limits his vision and his ability to quickly detect that the P51 has not pulled an immelmann. The P51 just flies straight for a "K" or so, and gently pulls up into max zoom. If the P51 does this "right", the F4U cannot follow him up. If he does, he's roped and dies. If he doesn't, and stays level/lower than the P51, he's just going to be a target for the F4U.
If this initial maneuver isn't enough for the P51 (or if the F4U doesn't pull a hard immelmann), he just sets up to do it again. And again. And again. There's really nothing the F4U can do about it. The best the F4U can hope for is to dodge the P51's gun passes, and do it long enough that the P51 pilot makes an error, or gets frustrated and thinks he can slow down and saddle up on the F4U.
The fine line the P51 plays with is extending far enough on each pass to be E-conservative for his reversals, but stay close enough to the F4U to keep the pressure applied between passes. The P51 can't allow a lot of horizontal separation, while the F4U will be making every effort to maximize horizontal separation. If the P51 extends more than about 3K, the F4U has time to think, and maneuver to his advantage. If the P51 stays much closer than that, he runs a real risk of falling into the F4U's trap.
In reality, I use this same tactic on 109's, P51's, and 190D9's; planes that are faster than me, so if they stay fast I can't catch them. I'll purposely "lose" the merge to get them to pull a hard immelmann, and scrub enough speed that they can't get away. Then I pressure the heck out of them to keep them turning. Then I shoot them.
And I'll do similar things to take away the E-advantage of a plane that attacks me from a higher position.
Getting an E-advantage over another plane isn't really very difficult at all for the most part, especially when you take into account how fights are "normally" fought in AH.
This is essentially the same thing the F4U can do to other planes that are "difficult" for the F4U to slow down and turn with.
Now, granted, this isn't how most F4U/P51 fights go. Which is why the P51 isn't really a very threatening opponent for many pilots. P51 pilots who fight like this will probably want to de-tune channel 200. Be that as it may, the idea here is to kill your opponent, not see if you can kill him while fighting the way he wants you to fight.
Having a faster plane than your opponent is a huge advantage, if you know how to use it.