Yes. They are a permanent boost so they count for perks, weapons, and conversation checks. I have all nine implants so I've tested and confirmed this to be true.
I started with END of 9 at creation, then got all 9 implants (although I didn't try getting endurance as the very last implant)
So either
(i) the endurance implant counts towards base endurance (my theory), and thus having 10 guarantees you can get all 9 implants (maybe less is required)
OR
(ii) the endurance implant does not count towards base endurance, and thus having 9 guarantees you can get all 9 implants (maybe less is required)
On a side note, implant costs:
4000 each for all 7 of the base stats increase implants
8000 each for the 2 special effect implants
Also, my INT was 4 (with a mentat withdrawal so it came to 3) and the doctor mentioned something about me really needing that stat / being really deficient in that stat, and so charged me only 3000 for it.