Buy Back of Flat

I have booked a flat during prelaunch by paying full amount (as the builder was offering attractive discount) and entered into an agreement via e-stamp paper (not registered). Now 3+ years are over the builder is ready to buy back the property and I found the deal is reasonable. He will execute similar e-stamp paper based documentation without registration. My question is

1) Can this be considered as Long term gain as the duration is more than 3+ years

2) As the property is not transferred can the e-stamp based buy and sale agreement be used for IT purpose or any other additoinal documentation we need.