Cushla isn't really an Irish name though, more 'stage Irish' used by Americans with some distant heritage. The Irish word is cuisle and literally means pulse or heartbeat and so if often used as a term of endearment "mo chuisle", my pulse, in the same way you might say 'my love' or something in English. I've never met or heard of anyone actually using it as a name, I have seen it lots on baby name sites of unreliable quality. In any case, the first syllable is pronounced closer to a "coo" sound than the "kuh" sound is expect to get from Kush.
If Kush is a genuine Indian name and you have heritage reasons to use it, I'd go ahead and anticipate explaining its origin and meaning quite a lot (what does it mean?) If it's just a sound you like without any particular significance, I'd be inclined to say it doesn't sound compelling enough in English to be a stand-alone name. It seems a bit insubstantial and made-up without knowing any history to it.
Personally I also don't like soft "sh" sounds in names so that could colour my opinion.