In all honesty, these old sedans will give you some trouble because their efi systems need to be in good order to work properly and all sensors need to be installed. Half swaps with mix and match parts won't work well. If the engine is overhauled with cheap parts then it will not run right.
Considering that you're a student and a part-time worker, I would recommend that you get a Mehran with a 660cc engine with auto gearbox. That's an easy to do swap, the car will give great fuel economy, will be cheap to maintain and you'll not be running after mechanics every other day.
I don't believe you have a lot of time on hand if you're a worker and a student so better to avoid these old janazas. They're all in poor shape and need a lot of upkeep. In case of 660cc engines I was reading some recent posts on the Mitsubishi Ek Wagon threads and people were saying that engines are for around 25k so that's not a bad option at all. Since our market is flooded with 660cc cars, you'll find plenty of engines and parts in used market.
And if you do go for 660cc engine in Mehran then get the whole system installed from intake to exhaust including all sensors and catalytic convertor. Then you'll get good fuel average (more than an original Mehran would've ever given you).
