Yes, I have done several times this Engine rebuilt of Khyber as well as other cars.
Approximately, last time, we overhauled my Brother's Khyber completely in January 2019. Currently I have 1 Khyber but its engine is still OK or atleast not bothering me too much.
My Brother's time, It costed around 50K inclusive of Mechanic and electrician Labor costs. Parts alone almost costed 35,000
Your case is not of just simple welding, in their term they call it shesha/glass (Engine sleeving)
In bore question, Some Pakwheelers have good experience with even 1.0 but frankly speaking, personally in my Khyber cars, never went above than 0.5
There are 2 dashboard repairers famous in Karachi. 1 is in Magazine line just Behined skin hospital but don't know their timings.
2nd one is also near you and also very famous. His shop is near Taleemi Baagh. Contact # is 0345-3400207