Hi
First assumption: i presume you do not know the credentials of the buyer. hence my view's are based on assumption that you do not know the credentials of the buyer.
1) Do not take such risks. I also understand the buyer predicament's( march 31, year end, stamp duty increase etc).
2) But the fact is that it is risky to do the registration and then await for payment.
3) Normally banks will issue Banker Cheques to the Seller at the time of registration only and banker's will collect the sale deed from the registrar office, once the registration is complete.
4) Also, ensure that the buyer pays the money in full at the time of registration only (no PDC's please).
5) it will be the buyer's responsibility to pay additional stamp duty.
Please tell the buyer that you are ready to do the registration the minute you receive your payment in DD rather than taking risks like registration first and payment later..