Doing the tappets/clearances is easy, just need a vernier gauge bit of paper and feeler gauges.
Simply set each cylinder in turn on tdc, insert the feeler gauge to measure gap between shim on top of valve bucket and cam lobe, then withdraw shim and measure, if the gap was too large then you need a thicker shim by the amount of the difference between the actual gap measured and the gap needed.
If one gap was measured at 0.75mm and it should be say 0.50mm, then you know the shim needs to be 0.25mm thicker(to lessen the gap between shim and cam lobe), if the shim that you then remove is say 3mm, then you would need to put a 3.25mm one in there.
Do all the measurements, marking each shims thickness as you remove them, you can then do swappsies, ie use a shim from one valve on another valve so long as the shims are unmarked/worn this is fine and done all the time, the last shim engine I did, I needed to buy 3 or 4 shims, at £3 each, even took old unworn shims in px!!
The shims are slightly off set from the cam lobe so the lobe imparts a slight turning action each time it is contacted, this keeps the wear dead even over the whole surface.
tabetha