Dear Sandeep

Predicting exact rank on the basis of score is not possible since a lot of it depends upon how many candidates appeared for the exam, how they have scored comaprative to you, etc. However, on the basis of pervious year's statistics, you may get an idea of the rank you may be allotted in the NEET PG rank card expected to be declared on February 15, 2018. 

In NEET PG 2017, the candidates who scored about 604 marks got an All India NEET PG Rank in between 70,000 to 75,000. 

Hope it will help! Good Luck.