I'm not a wood guy Lloyd, but have seen lots of cracked and shattered stocks. The oil staining at the apex of the lockplate inlet is very typical, but I agree there is discoloration which looks to be down the middle of the head of the stock. I don't know if this was an intrinsic defect or the results of 100 years of oil.
When everything is apart it will be more clear, and please let us know.