what temp do i need to smoke a deer roast

To what degree of doneness are you looking for?  Are you cooking it to be done as a roast beef, or to fully smoke it to either slice it or pull/shred it?  For a roast beef like temp, I would pull it off at 145-150.  To slice I would wrap it in foil at 165 then pull it at 190.  To pull/shred I would wrap it in foil at 165, then pull it at 195.  In both instances, let it rest for an hour, wrapped in a towel, in a dry cooler before either slicing or pulling/shredding.