Have you tried calling the West Carroll Parish Library? I suggest doing that before you give up.
From what I understand, the newspaper in Oak Grove experienced a fire some time back, so I'm unsure if any obituaries from them, back that long ago, are available. I don't even believe that they were microfilmed before the fire. I was told about this fire when I went to look for records I would call the Oak Grove paper to see if they are aware of microfilm copies, even if they are outside of the Oak Grove area.
Outside of looking for microfilm of the newspapers, the only other option I can think of is locating the oldest funeral home in the area to see if they can give you a history of the funeral homes in the area, and whether they got absorbed by a current one, or dissolved.
Have you read the book "Between the Rivers: A West Carroll Chronicle" by Florence Stewart Mckoin? It was published by Claitors, who is a book store in Baton Rouge that has online ordering. This may provide you with some perspective.