Hey Ivanhoe, I'm glad you're enjoying them.
If you're using my roster that came with the 07 mod, I think the most recent models.big found on this site would work best. It will be fully compatible with the 07 mod models.big once the patch is released in the next couple days.
As for rating minor leaguers, it's a tough thing to do. Not all players have scouting reports, so I basically went by stats to rate a bunch of them. It's a staggered system, so I tried to have AAA players rated higher than AA players, and AA players rated higher than A players. I'm always checking out new scouting reports to make sure players have the right pitches, etc. I have a membership to scout.com, and that's how I get most of my scouting reports.
If you want to suggest that I add any players from the Prospect Handbook, I'd be glad to take a look at your suggestions. Remember, I won't add guys that are slated to start the 07 season in rookie leagues or short season ball (guys like Dellin Betances, Kyle Drabek).
Let me know via email or PM and I'll gladly take a look at whatever you've got! Thanks for your interest. :)