Could you estimate Napoleon's (or other historic persons) Elo on the base of his known games? I wonder if there is a possibility to calculate/estimate the Elo rating Napoleon would have today by analysing his known games? Is it possible at all to calculate an Elo rating only with some documented games, if so, how many games would you need to give a good estimation? Is there a list of Elo estiminations for historic persons which are known as good Chess Players before Elo rating was used?

I wonder if it is somehow possible to estimate the strength Napoleon would have even it is not an Elo value. If you could theoretically play a game against him today, with all the chess-knowledge and strategies discovered after his death, how good would you need to be to have a chance?
There are efforts to calculate the playing strength of pre-Elo players on the basis of their games. See for example this paper by Kenneth Regan.

But if you look at the "intrinsic performance rating" of historic players on page 5, you will find that they vary quite a bit even for the same player at different points in time.  

Personally I find it quite unlikely that the performance of Zukertort or Steinitz varied by over 300 points against different players. 

To estimate the playing strength of a player who left only very few (and selected at that!) games, these methods seem to be nowhere precise enough.  

Edit: I found another paper but this method seems to end up with a rating between 2700 and 2800 no matter what, which doesn't inspire much confidence.