The good thing is at least in the past Indian T-90S didn’t usually have markings at least according to the photos I’ve gone through. Now unit emblems and numbers appear to be becoming much more common.
Tojo72 is correct there are differences between the Zvezda kit you have which is a T-90A and the Indian T-90S most of it in the turret. The big differences between the two are T-90S doesn’t have infra-red dazzlers on each side of the main gun as the Indian Army found them to be outdated. The Shtorta-1 passive/reactive protection system armor is a different version on the T-90S then what the Zvezda kit includes.