the valve clearances are called tappet setting in Pakistan, the correct way of doing them is with engine in place and renewing/swapping around the bucket shims. A good time to install new valve seals too - if they need attention. The lathe machine route is just silly IMO, anytime the head is removed from the engine, the head bolts should be checked for stretch and renewed if necessary, the bolts are Torque to Yield type. Our mechanics have no clue what a TTY bolt is, and stack washers under the bolt heads to take up stretch - what they dont know is that the bolt is now weak.
Timing is done by use of a dial gauge to measure the plunger stroke of the pump at engine TDC1. Cold start vibration is also caused by faulty timing, mostly because of bad cold start device or bad timing or both.