1) The property has been purchased by sale of ancestral property and hence the property will continue to be ancestral.
2) Your father's sister's cannot claim any share in the said property now as your grand father died in the year 1971 and hence the property will be governed by Section 6 of Hindu Succession Act and its amendment in the year 2005.
3) Your father and his brothers (Including the children of deceased Uncle) can dispose of this property to any buyer who is interested without need for the daughter's or their children being parties to the sale transaction.
4) Technically, your father and his brothers(including the children of deceased elder uncle) will divide the property in to 6 shares initially.
5) If the property is being sold, the other brothers can simply sign the sale deed and authorise the seller to issue their share of sale proceeds directly to your father.
6) If your father and his brother's are not selling the property, but instead want to settle amongst themselves, then they should execute a registered settlement cum partition deed .
7) In the said registered settlement cum partition deed, Since it was your father who used his money to construct the house, the other uncle's can settle their share in favour of your father by renouncing their share in favour of your father
Hope this information is useful.