In the threads about buying a used battery from a junkyard there was concern about whether or not the long term storage might damage the battery.

I don't think it will be a problem.

What I've read about long term storage says that the 12 volt battery has to be disconnected.

Assuming the car got to the junkyard following a wreck, that was bad enough wreck to total the car; it is now standard practice for fire departments to cut battery terminals before they do anythign else to prevent the airbag from killing a paramedic.