GPA with consideration

Hello Lawyers!! I'm in need of this info. Please guide. Land : Tamilnadu Deal: POA with consideration. I have paid for a part of the land. The land owner is willing to give POA. How to do it? There is something called POA with consideration. It says stamp 4% on consideration + 1% reg charge on consideration . My question is this better than a GPA and what is this percentage mentioned ?? On the market value of property or on the part payment done to get a GPA? Please explain . Thank yoi