1st check internet for engine variants and transaxle available for your car model if any of engine suits your desire of performance search the market.
visit the kabarya market in your areas and do the research of what type of engines are available later check the market of new spares for the same engine as in kabarya shop so if required you change parts with new ones. buy engine coupled with an automatic transmission complete with ECU n wiring. swapping engine n auto transmission require careful rigging of ecu
FYI petrol will be Rs. 120 per litre by Dec 2013 and US$ 1 will be PKRs. 110 so make choice carefully.