Query on calculation of Indexed cost of property

How to calculate Indexed value of Flat in in 2016-17 in following case as the payments are made in different financial years having different Cost Inflation Index (CII). Whether the legal costs of purchase (registration fee, stamp duty etc) are also to be considered. indexed and if so, how to do that in case given below. 1) Purchased a Flat as first owner from Army Welfare Housing Organisation 2) Purchase price of flat – Rs. 7,11,900/- 3) Sale Consideration Value - Rs. 3,62,323 4) Flat was allotted on 23.03.1998 5) Payment details are given below. a - Booking amount - Rs 20,500/- on 02.03.98 (FY1997-98, CII - 331) b - First Part Payment - Rs. 20,000/- on 30.03.1998 (FY1997-98, CII - 331) c - Final Payment - Rs. 6,71,400/- on 16.04.1998 (FY1998-99, CII - 351) d - Legal (Sale deed transfer)- Rs. 41,300/- on 23.02.01(FY2000-01,CII - 406) Please note that Sale Consideration Value Rs. 3,62,323/- was estimated by Authorities as cost of specific unit for Stamp Duty purpose, excluding the cost of common facilities My specific queries are – 1. Which CII value is to be considered - 1997-98 or 1998-99 2. Whether the legal costs of purchase are to be considered, and if so, should it also be indexed and which financial year CII shall be used for indexation of Legal costs.