I would go along with Easter on this, it is not in a "wet" area, it was running OK when the damage was noticed so the cam belt was still in place with no valve or drive train damage. It looks like the nut has undone and damaged the case. Torque it up and lock it, check the drive belt condition, temp repair the cover and use it until the replacement cover arrives. Fairly certain it's not as bad as it looks, not an engine change but a competant S&S engineer will know. I assume a trained Morgan dealer will know for sure?
