My goodness, two threads in the same week for which X1: Isle of Dread is the answer! (The other being AlSiH2O's circumnavigation thread.)
I have found that simply changing the names and sometimes the races in modules makes them all but unrecognizable to players. Another nice trick is the flip the map. You heard me - take that X1 map and turn it 90 degrees to the right or left. Do the same with all the dungeons. Except for players with photographic memories, that should do the trick.
Use the Isle of Dread for the island. Use Dwellers of the Forbidden City for the ruins. And cap it off with Hidden Shrine of Tamoachan and Forgotten Temple of Tharizdun for a set of buildings and that they can use to teleport back to home.
Of course you will have adapt them very liberally.
And the blurb: "Somewhere in the heart of the steaming jungle lies the answer to the whispered tales -- rumors of a magnificent city and foul, horrid rituals! Here a brave party might find riches and wonders -- or death! Is your party brave enough to face the terrors of the unknown and find -- the Forbidden City!"