Well, depending on were in the world you live parts aren’t as available as in other places.
I live in Sweden and when i swapped my oem cam in my Us spec 240z for a Schneider cam (head had been rebuilt in the USA and the rebuilder wasent as exact/good as he should have been) the lashpads had to be adjusted a bit to get the exact wipe. I left the pads and my measurements to a mechanical school and they grinded them down to the size i wanted (then I could take some off if needed by myself with a small file.
For me it would have taken 2-4 weeks or so to get correct lashpads from the US. This way it took me a couple of hours.
I started with size 190 (that was all that msa had to offer) but can’t remember were i ended up, there were not to much that needed to be taken off the pads but still... better to aim for the exact same wipe on all then just make it work.
//Andreas