RR - Thanks for creating a separate thread. I started to look at the Maestro's milestone movies and I am just half way through. I was expecting to see some official database (Film association, Music Director's Union, etc.) containing this information. Karthik Raja should collect the accurate data and upload to Raaja.com which is the official website. It's a sad state of affairs that Maestro's official website is not even up and running. We live in a media frenzy world and his children can at least get these basic music sites checked and updated regularly. His major milestone movies are listed below. I believe the specific milestone is hit when the actual soundtrack was recorded by Maestro and not the movie release date. Dubbed films are counted as separate milestone because the sound track is recorded for the second time with new playback singers and orchestration.

100th - Moodupani (1980)
200th - Bhagavathipuram Railway Gate (1983)
300th - Udhaya Geetham (1985)
400th - Nayagan (1987)
500th - Anjali (1990)
600th - ???
700th - ???
800th - ???
900th - ???
1000th - Tarai Thappattai (2014)