Capital gain tax on my sale

Dear sir, I have booked a under construction flat in Bangalore at a price of 6000000 (60 Lakhs) in 2013. Flat was ready in 2015 and builder issued a possession letter in Nov 2015 and same is registered in march 2016 with undivided land value rather than full value. Hence i ended paying around 3 lakhs stamp duty and registration. In Sale deed value shows 1250000 where as in EC market value shows as 4800000(48 lakhs). I did interior worth of 5 lakhs and rented the flat. All this amount paid was white transaction no cash is paid except for interior done. I have aken loan of 48Lakhs for this property. Now I am planning to sell the flat and want to register the flat in buyer;s name after march 4th 2018 which will make 2 years to become eligible for long term capital gain. Sale price fixed is at 83Lakhs. Buyer wants to register it at full value. Now what would be my long term tax on this ? is this actual value i paid isconsidered as cost of acquisition which is 60+3+5 = 68 lakhs or the price mentioned in my sale deed in 2016 which 1250000 land value be considered ? . I have a full proof of bank transaction on flat done Please guide be in this . Based on this i will take decision to for this sale or not as I dont want end up paying a huge tax as i am a salaried employee.