Everything 3Cforme says is true. I'd still try calling back- a number of times, if required- to get an agent who can find the inventory or one who will try and make it happen. It can't hurt to try. Good luck.
Cheers.
However, the OP can ask to be rebooked on the flight of his choice, regardless of inventory due to 240/80. All AA needs to have available are actual seats. Now, if the 777 goes away as speculated on here, then that is another story.
But, assuming the 777 is still flying that route when the OP is traveling and they have seats in ANY inventory available, AA should/will put him on it
Calling AA, armed with info is good advice
Cheers