seeing your ride in for sale section , i will strongly recomend not to buy santro and its like chnaging from a pajero to alto.
Your car old car is rock solid , where santro is like a tinbox.
If you have desil in old car it will be giving you better performance than santros petrol engine.
put 5 ppl in your car and drive any hilly area and then do same with santro and see the difference.
plus your car get much more space than santro and last but not least
toyota always had much better avilability for parts around the pakistan.
i will say if you are going to spend Rs 250,000 - 300,000 may be look for 82/86 corolla or if your budjet is around 400,000, a 95-96 civic is the best option