Torezu's post in Out of Memory was marked as the answer
If you aren't getting more than 950MB on the in-game attrib screen, you're still not using 64-bit Java. You have to not only install it, but run the game with it. Another clue is how much the launcher allows you to allocate. If it doesn't go to 2 GB or above, you're still using 32-bit Java.
Torezu's post in World Crashes on Startup - Help!! was marked as the answer
If you're running Windows 7, there are likely to be backups (right-click on folder, click Find Previous Versions). Otherwise, you can try getting an NBT Editor and removing the item from your inventory from outside the game.
I moved this post to the correct place. Future bugs for custom modpacks such as this one go here, while bugs with the launcher itself and official modpacks go on the Tracker.