Kanupp utilises vintage 1960's technology, but even so, Pakistan could struggle to duplicate the reactor due to various industrial manufacturing capacity deficiencies. However Pakistan does possess a fuel fabrication line dedicated to Kanupp type reactors, it has some experience in procurring and manufacturing spare parts, and its reprocessing plants are designed to handle Kanupp style spent fuel.
India's duplication of RAPPS-1 and RAPPS-2 in the 1970's and 1980's are instructive here. It took India 20 years from the completion of RAPPS-2 (which was partially built with Canadian assistance) to the wholly indigenous RAPPS-3 (220MW(e)) which came online in 1990.
It would probably take Pakistan just as long, 15 - 20 years. Even so, Kanupp could be scaled initially to a 100 MW(e) - 150 MW(e) to even up to a 200 - 220 MW(e) reactor. Built in modues of two you're looking at 440 MW(e) for power and desalinisation, with export potential. Such modules may even be cheaper and more job creating than buying in CNP-300 PWR's.
Kanupp Candu technology is well understood. India, South Korea, Argentina and China can all to various degrees replicate it. Assistance from China would be helpful. One large impediment remains procurement of uranium fuel, which is why I would stress emphasis on co-operation of friendly countries, and experimental sea based extraction methods. Other cons are it wouldn't help much in the development of a prototype naval propulsion reactor ( they rely on integral PWR's) or development breeder reactors. It would certainly draw resources away from those projects if developed from scratch, but buying in those technologies was always the least expensive.