There is not a pre-setup set of rosters for this, I think due to the paucity of statistics and records and even the laxity of the organizations for this time era.
What I did was relied on
https://www.baseball-reference.com/ for the team rosters based on their records for those years.
When you start a season in that era, export league rosters, and edit the files by opening in a text editor or spreadsheet and editing the team field to the correct 3 letter code for the team, then importing the file into the game.