You might get away with it (IF it happens to run okay afterwards) but the right way to do it is testing And resetting the injector that you took apart/opened.
There`s not much chance for the settings of the `newly built` injector to randomly* fall to around where they HAVE TO be (= right at factory specs).
Quality reliable testers with the perfectly ideal dial range aren`t cheap
It is also quite challenging (and risky) to keep&maintain the surgically clean environment that rebuilding the injector absolutely* needs.
Add all that cost, time and hassle up and maybe you are at the prices that the reputable reliable PRO service would cost...
If built well, they will be perfectly set and serve you well and reliable for about 50-75000 miles depending on condition of fuel... maybe the tank, filter, injection pump circumstances can also improve or worsen that number, IDK.
I also have a couple of sets that need to get rebuilt and if finding those adjuster shims/washers were much easier then I would possibly have a second attempt at doing it myself... but until then I would prefer sending them to a reputable shop/mechanic who deals with these type of injectors on a daily basis, professionally. Ideas and links are welcome!
Here I would like to (re-)share a
link that I got long ago from a forum member. This good article is about all the details around rebuilding the injector.
https://vincewaldon.com/2008/10/29/h...idi-injectors/