There are a ton of pics online now, and from the looks of things, the vault flooded with mud as high as the beltline. There were some shots that look like there isn't much more than a few spots of surface rust, mostly the mud LOOKS like rust. Interior is certainly trashed, but all the fabrics are available through restoration companies. The drivetrain isn't really a problem to fix, it's not like the motor was running when it filled up.
That said, cleaning it out prior to starting work would be a stone bitch.