Developing roster files, need ratings source
 

I was wondering how you determine ratings for each player in the ROSTER file. I would like to develop a file myself but would have problems with some of the players since I did not know what there abilities were like. I searched the internet to find ratings of players in the 70's but came up empty. Can anyone advise me in this pursuit. Again, I would like a ratings source for past players to make my own files.

Thanks