After doing some searching, I realized there are multiple family trees that list Benjamin F (Franklin) Smith as dying on May 9, 1958. But, i haven't seen any that list a source for that information.
But it appears to be the correct person, as the birthday matches up.
If you go to the following tree, and click on "view all comments", there is a little obituary that someone has posted.
Is this the Benjamin F. Smith you are looking for? You may already know all this, and I may be confused about what you are looking for. :)