For any reliable rebuild - first find a mechanic who is reasonable and has a clean room/space/shelter to work on the engine, Now the owner in Pakistan will have to get the following few additional parts for a proper rebuild to take place.
1 - Torque ratchets x 2, 1 high torque and one low torque
2 - Genuine Toyota Form in Place Gasket FIPG
3 - Engine enamel for block (you can choose flouroscent yellow if you like)
4 - Dial gauge or even feelers work to select the correct gasket thickness
5 - lots of assembly lube
6 - tap and die set to clean every thread on the engine
7 - make sure the machinist knows his work - diesel engines have a deep scratch hone on the cylinders.
the parts list other than the usual "parchoon" should include.
new cylinder head bolts
new con-rod cap bolts
new flywheel/flexplate bolts
new crankshaft pulley bolt
Follow Toyota manual procedure and you wont have any issues down the road. Dont let the "cheeta qism ka mechanic" use "vashurr" on the cylinder head bolts to make up for them stretching - they are useless after one use hence the term torque to yield bolts.
Dont let the engine idle for centuries - as the first 20 minutes of startup are the most critical for bearing seating - hold at 1500 rpm for 20 minutes, use the engine like it should be used (no thrashing tho) to break it in. Idling it while the haleem cooks or you get wrinkles on your face will make sure the rebuild is useless as the rings will not seal up against the cylinders.