swapping an engine from carb to efi is not that difficult if you can manage to get hold of a decent EFI engine with ecu, wiring & sensors PLUS an electrician with bit of brain to do the wiring. changing engine number in the book is not a task if you buy an engine surely from imported scrap with receipt from yard.
search threads with tags, efi, swap, engine and you be able to locate a Islamabad / Pindi member doing a successful swap of an efi engine with all wiring properly mapped.
swap will cost you anything between 125,000 to 150,000 for a 1300 CC EFI engine. It will be another task to locate an engine which will mate with your current transmission - power train.
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If all that (surely) is not economical time consuming task, rebuild the very same engine with maximum Original parts, rebuild the engine to proper specs, clean the cooling line in engine block head, put back thermostat valve, use coolant made in bottled water, clean the radiator, rewire the cooling fans to work on automatic and engine will be good to go for another 150,000 - 200,000 kms with proper maintenance change of air filter oil filter & engine & transmission lube changes