Only GPA on my mom's name, Can I register it Now.

Hi, My father purchased a land(40x15 SqFt) in bangalore in 1990 from a person through GPA and GPA was made to my mother name. Later in 1992 we built our house and we are residing there from then. No Stamp duty or registration was done during the land purchase but Sales deed/agreement was done along with GPA on my mom's name. And now the person from whom we purchased the land is no more. Due to my father death in 2000 we were in financial crunch and was not able to register the property earlier. Now I am planning to register the property for our safe future. So can you please guide me how can I proceed further. The documents that I have regarding the property are :- -> General Power of Attorney on my mom's name. -> Sales deed/agreement done during the land purchase. -> Documents related to Betterment charges paid to BBMP -> Khata Certificate of the property on my mom's name Are there any issues I need to face if I go further in Registering the property now and should I pay the stamp duty now(According to the current market value). Your advice is very important and glad to me. Please do the needfull. Thanks.