1) The GPA is attested by Indian consulate.
2) For legal purposes the nephew should register the GPA at Sub-Registrar office by paying Rs3500-/- as registration charges.
3) Registered General power of attorney are preferred over unregistered GPA.
4) Agreement of sale should show the entire sale consideration (i.e 50 Lakhs), so as to enable you to get maximum loan amount from bank
5) Also please check the fair market value of the property from sub registrar office as banks will give loan amount either on agreed sale consideration value or Fair market value , which ever is LOWER.
6) So prior to entering in to agreement of sale, please check with sub-registrar office on fair market value of property, as it will impact your loan sanction amount.
7) Registration charges are 6% of sale consideration value or fair market value which ever is HIGHER.
Hope this information is useful.