The shim size on each valve varies.
You have to measure the valve clearance for each valve, and if it is out of spec, note how much the difference is. The existing shim for that valve then has to be measured, and the difference (positive or negative) has to be added to or subtracted from the thickness of the original shim to get the clearance back to spec.
I think in most cases the shim will be less than 2 mm thick. As it is hardened, a surface grinder will have to be used to reduce it to the correct thickness. You do not need to buy shims next time 7.5 m die pins will do fine if you have the facility to do the parting on a lathe with a grinder.