Half of the motherboard and part of the chassis is rusted in the area around the battery. The battery itself was lying loose in the case, all rusted too.
The power supply, CRT, hard disk, superdrive and memory board appears intact (visual inspection only).
Obviously, I haven't tried powering on.
The case is very yellow.
I've thoroughly cleaned the keyboard/mouse and borrowed it for the MacSE (which has a key missing) and the MacPerforma450 which doesn't have a keyboard.
I could try to swap the HD and superdrive with the MacSE to have one working system and recuperate the data on the HD.