Hey there

You have decent academics score and thus your entrance exam score will decide majorly your admissions to top MBA colleges. So focus on your CAT and other exams. For IIM Calcutta it's top iim and thus cutoff is high. For foreign colleges GMAT score is considered with good academics.

Check details of IIM Calcutta

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.careers360.com/university/indian-institute-of-management-calcutta/amp&ved=2ahUKEwj06cfplKPpAhWlxzgGHSyrD3QQFjAAegQIAxAB&usg=AOvVaw3EzIySTc29m0RGe60_M0Hp&ampcf=1

Good luck