Should I retake the GMAT? Confused!!

Hi!
I took the GMAT today and scored 750 (Q48 V45) IR 7.0

I am an Indian undergraduate student studying in Singapore. I am looking to apply to the Indian Institute of Management Ahmedabad, Calcutta and Bangalore for their respective 2 year programmes. From what I have seen on the IIM Ahmedabad website, they convert the GMAT score to a base score. Then they compare this base score with other applicants taking the IIM's own entrance exam, the CAT. The conversion for a 750 on the GMAT is a 267 on the CAT. Is it enough to get in? (I realise that it may not be. Inputs appreciated) Or should I retake?

What happened:
The bottomline is that I screwed up my Quant and even though the score shows Q48 it really is a 76 percentile. I had been getting 770s and 780s in all my GMATPrep tests and feel that the low Quant may be a one off thing, and that I can improve if I give it another shot. The other side of the coin, however, is that will the schools look down upon multiple attempts (I used the "send score" option before the exam) ? Another question is what if I get a 750 or below again, will that be looked down upon as a lack of improvement?

Practice tests:
Manhattan:
1:720
2:710
3:690
4: 760
5:690
6: 730

Kaplan: 760

GMAT Prep:
#1:750 (Q48)
#2: 770 (Q51) retake: 780 (Q50)
#3: 780 (Q50)
#4: 770 (Q50)

In conclusion: Is the score good enough for IIMs? Should I retake? When should I retake(I feel the sooner the better)?
I would appreciate any help in this matter.