Yeah if you can work on cars, you will be fine working on the bike. The washer stacks is pretty much the only way with these bikes. I think the newer cobras have a different style clutch but that has only been in the last few years. It may be less maintenance
but I'm not sure on that. As for measuring the stacks, I just use a good set of calipers instead of mics. The calipers just make it easier to measure. I usually get the stacks within about .002~.003 of each other. If you are happy with the way the bike runs now, then I would suggest you leave the same style and size stack that is in it. You can put a zip tie thru the washers when you take them out so they will stay in order. Then stack the new washers in the same configuration and overall height. A new set of washers should last a long time if he is just riding in the field and you keep the oil changed.
BTW, not sure why they moved this post to the Chinese section?!?!? Cobra's are not Chinese! This may fit better in the General Mini section.