Capital gains tax on sale of property

Dear Sir,

I have finalised a sale deal in respect of my flat having area of 82sqm in Delhi which I acquired in July 1986 at a price of Rs1,34,000/-.The agreed sale price is Rs1.26 cr.The sale will be done in April 2018.Its fair market value has been assessed at Rs19 lakh by a govt.approved property valuer as on 1-4-2001 and indexed value for current FY about Rs 52 lakh.For next financial year also,it is not  going to be as much so as to mask my LTCG.I can not show receipts on cost of improvements done etc.

I most humbly seek advice on following points,

1 What are the ways to minimise or  save the tax?

2 Can i invest some amount in bonds  and balance in a housea house?

3 Will i have to remain invested in bonds for 3 yrs or 5 years

4 What are criteria for assessing fair market value?Can i have it reassessed for a higher FMV so as to reduce tax liability.

5 Any other advice on the subject.

Thanks a lot,

S C Goswami