Sale of property by pio holding foreign citizenship

If the property was inherited, then the cost of acquisition for you shall be the cost price for the previous owner, and indexed accordingly.

The case law in your case is given below

Mrs. Prema P. Shah v. ITO [2006] 100 ITD 60 (mum)

You can pay advance tax for capital gains. The tax rate after adjustment of indexed cost against the sale price would be 20%+ Ec 3%

Cost at which the proprerty was earlier purchased by previous owner will be your cost and then inflation effect needs to be given. Yes it ll be long term capital gains. You will have to pay TDS @ 20.6% on net capital gains. 

While I thank valuable replies, I may mention that the property was bought by the previous owner more than 200 years ago and there is no way to find out the price paid. What do I do in this situation? If I make an advance tax payment, will the Income Tax assess the then price of  the ancestoral property according to their guidelines?

You can get the property valued by Govt approved certified valuer as on 1/4/1981 and then apply the cost inflation index.

While I thank you for the advice on hiring a property value assessor, I may mention that the amount of sales proceed is significantly low as the portion of my share of land is tiny. I am trying to make spending wise avoiding any unnecessary expenditure.

Will it be possible for me to pay an advance tax at a rate of 20%  and then get back the excessive tax paid while I file tax return. How do I pay advance tax at 20% as paying tax abroad is by filing a Tax  Return before the end of the fiscal years and it is before April.

Advance tax is paid on the basis of estimate. You are first required to compute the long term capital gain before arriving at the advance tax figure. You may use market valuation method whereby you may find out the likely value of your property by comparing with the value of the property situate in the vicinity of your property. If the cost price is unknown, the AO does not expect the assessee to have an accurate figure. An approximate value is good enough.