I'd say around 10 is about right of each speciality. So 10 chaplains, 10 tech marines and then 10 apothecaries. Of those there's probably 5 to 20 more candidates and understudies for the position. So at a minimum 45 specialist personnel at a max around 90. Of these each individual probably has 30-70 support personnel. Meaning each head of the command speciality has thousands of support staff to get stuff done.
Librarians probably have a lot limited number due to their nature and strict management. 37 chaplains is a possibility, but that's a lot of men of the faith in one place.
"Ambition is the biggest killer of Momentum"
Starting afresh with my Chaos Space Marines.
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Project Rebuild, Reboot, Recycle:
Stripping, rebuilding and remaking my Guard army.