The superstructure is aluminum, which is why the United States is relatively light for its size. If it is sunk as a reef, I wonder if the superstructure will outlast the hull.
I couldn't find anything on the depth they are going to put it at, but if it's like the Spiegal Grove, it'll be in fairly easy rec dive range, which I believe is 75 to the top deck and 130 to the keel. If it's like the Oriskany, that's more of a tech dive at 145 to the flight deck and 210 to the keel.