If no legal heir of your father have any problem with this arrangement than all your fathers living heirs i.e. you all siblings and mother can make a family settlement deed with your fathers brother giving him that portion of land according to your fathers wish. Specifically mention in the deed that it was your fathers oral will if all the legal heirs sign and consent along to name of your uncle then documents will be registered and the property shall be transferred accordingly.
Since on death of your father without will the property according to law dissolve on his wife and children , also it is very difficult to prove a oral will in court so in case all are ready and accepting the oral will then you can draw this family settlement deed based on your fathers oral will. The necessary condition is that all the parties should agree to this if any one among children of your father or your mother can challenge the oral will. So consent of all the legal heirs is required.