Can I get CSE at any good private or government college at 76.7 percentile?

Well, you can get into government college in this percentage that is also good result. Apart from it, college doesn't matter for CSE students.

For 75 percentile you will get other universities with CSE branch. But for NITS or IITS it is not possible.

For ST I think above 95 (to get into other state best NIT)

For home state NIT For ST people 93 percentile and above can do the work .

For SC people 94 and above for home state.

And 95 above for ot