I'm fairly new to OOTP, but the first thing I did was set up a historical league starting in 1973. Check out the Mod's listed in these forums. (You can also go to the OOTP Baseball web site, It's
www.ootpbaseball.net)
I believe the Lehman database will give you everything you need in terms of a historical player database. It might end at 2006. When you set up your game, I'm pretty sure you can choose to have the game automatically assign players to the historically correct team in the historically correct year. This would free you up fromhaving to import new rosters. But I don't know how successful you would be at controling roster changes made by computer managers. You're probably familiar at least with the existence of mod's. You can download additional mod's that include historical photos, uniforms, and ballparks. Some of the mod's come with instruction (txt) files. I believe the OOTP Manual also gives some generic instructions for importing mod's. There's probably a discalimer in the manual pointing out that OOTP hasn't officially approved any mod's. Don't let that bother you. A majority of the mod's that exist have been created by long-time players of OOTP; and these mod's have pretty much stood the test of time (and player feedback).
Hope this helps (I apologize if it doesn't).
Gyro