Interesting to consider what you would do if you found it? Presumably you're in the wilderness with a 40 pound chest. Your car might be fairly near, as Fenn makes clear when he notes he was 80 when he made "two trips from my vehicle" to the site. So if you're fit or have help you can probably get it back to the car (40 pounds is a lot to carry in hiking terrain). What happens once you do? How do you claim title to it…
I for sure would not tell anyone about it.
But you would need to if you want it for it's moneytary value. Even selling in piece by piece on a black market, which is quite hard to do, will require you to advertise it.
However my guess is that whoever is smart enough to find it is smart enough to solve this problem as well.