You can also check out SM shetty's IB and Gopal sharma (ICSE) Two of my friends are happy with SM shetty's IB, and feedback from one of the tution teachers around Powai is that Gopal sharma's teachers are decent, level of education is also good. Though I havent spoken to anyone on this subject. When I went to chk for my own child about 4 yrs ago, I found the school very drab and dusty. Maybe things have changed since then. You will have to go and see for yourself.
Another option is Prime academy (but my experience with them wasn't great) check my feedback in another thread. But still, I would advice you to go see for yourself and decide based on your judgement.
Another good school in Powai is Vivero International(only till Sr kg though) My friend has admitted her kid in nursert and is very very happy with the school. Its far more expensive (rs. 1.2 lac for the year for nursery)
If you are willing to let your child travel to Shere-Punjab, theres a school by name Tridha. They have a very different learning pattern and parents/kids are very satisfied. I dont know whether they have a bus service till Powai though, you will have to go and check for yourself.
Have heard Nahar building is not yet ready and will not be for another year and they are deferring admissions to June-2014. So pls be careful, Pawar public school had similar issues last year. HFS and Bombay scottish are very arrogant and deal in a high handed manner.
Poddar, Garodia are 2 more options in IB..supposedly expensive but good..no harm in checking out. I didnt, so i cant say anything with conviction.
All the best..and dont worry, something will work out and incase you dont get a school of your choice this year, you can try again in Jr kg. Admissions from Grade-2 get difficult.