Hi,
You have gotten some of the concepts mixed up.
1. You can convert even if you hold an OCI.
2. You need to be hired by a company and only then can the FATA be applied for.
3. FATA (Indian version of Validation) is only issued to TRE, TRI, Line Capts, and Flight Instructors. You also need the ratings and approvals on your parent licence to get the FATA.
4. Once you convert, you can apply and work in India on your OCI (I know quite a few OCI Holders flying in India after converting their licences).
Regards,
MBhon