dont trust these mechanics, they will always try to get something for themselves.
Khyber's engine is very simple to rebuild, most of the mechanics can do it, consult others and make a deal with them for only labour charges. You must be present when he opens your engine and check everything whether it really needs replacement or not. then buy those things from a good spareparts shop (reliable) at a different place and bring that to mechanic telling him to change it in front of you. Only this way you can control your cost.
You will need only rings, gas kit, tappet cover patti, gas kit cover patti, some greece and oil, May be valves and pistons also if they are in really bad condition. Nothing else.