Khyber/Mehran r both good, I mean U will get a Mehran of newer model & Khyber is better than Mehran.
But if I were @ ur place then I would have gone for a Accord 83-85 model or Galant 84-86 model, & got them converted on CNG, these cars are heavy on petrol but CNG will help in that case, these cars r old but once u'll drive them U'll love them. These cars r heavy on maintaince but a part once installed will last for a longer period compared to a part installed in Suzuki.
But if u wanna go for Khyber/Mehran then I already told u the situation