Advance ruling versus lower rate of tds certificate

For the last few years I have become NRI to USA . I had purchased properties at Greater Kailash area of New Delhi in early eighties . I am planning to sell one soon. The buyer is asking for TDS to be deducted at 22 -23 % on sale consideration ( which comes to several crores ) . However  Long term capital gain tax after indexation  will be much less . Is it possible  or advisable to get an Advance Ruling from Income tax Deptt.  OR  should I try to get a certificate of lower deduction of TDS from AO . I had been filing my tax return at Delhi for  years.