The facts of your case suggest that the land acquisition proceeding has lapsed. Your land was acquired in 1976. It is not clear that the concerned authority had published a notification in the gazette. If the government had published the notification for acquisition of your land but it did not take possession and pay the compensation.
Currently, you have possession over the land. In devoid of physical possession and payment of compensation the proceeding of land acquisition has lapsed. In this scenario the government should initiate a fresh proceeding under the provisions of Right to Fair Compensation and Transparency in Land Acquisition, Rehabilitation and Resettlement Act, 2013.
In your case the concerned authority has not passed any award of compensation under Section 11A of the Land Acquisition Act 1894.. Award of compensation is mandatory for the acquisition of land. Without passing the award and taking physical possession of the land the acquisition proceeding was deemed to be lapsed [Budhi Nath Jha v. State of Bihar].
The government has not acquired your land and not taken physical possession. Therefore, you can build a house on your land because you are still the owner. You can file an application to the Tehsildar court for the demarcation of your land if you want further clarification about the current status of your land.