Patta vs sale deed measurement - which is valid?

Hi all We are living in tamilnadu in a land classified as grama natham which was bought before 30 years. It had it's patta issued before 20 years. We built a house before 15 years and living there ever since. The total measurement in our sale deed is 1044 sqft. And our patta measures 1475 sq.ft. but we were not aware of our measurements. Before our house there was a land which was vacant all along Now a person had started construction in his house. As there was a dispute between us we took out document and found out that our area is extending into his area by about 80 sq.ft. But according to his sale deed measurements his boundry area is correct.But even though his sale deed measurements is around 964 sq.ft. his patta measurement is only 800 and his ec reflects the same. My questions are: 1. If surveyor comes which measurement is taken into account - is it sale deed or patta? 2. How is his EC and sale deed measurements are different? 3..How is his sale deed measurement is higher than his patta? 4. He has constructed 2 floors already. Can I get my land back if I file a civil suit now or can I only get compensation since he would have finished his construction before I file a suit? Thanks in advance