I have been out of the loop on P99 for a while, so I went forum searching.
Looking into the AC issues, I can see how it would be a massive undertaking to get AC values correct if the original (or at least close-to-era) tables are gone.
I'll do some more looking around, but I did manage to find this post from an EQ DEV regarding AC:
https://forums.daybreakgames.com/eq/.../#post-3078126
It's Daybreak, and it's Apr 16, 2014, but worth a look I think.
I also vaguely remember a post a looooong time ago that blew my mind about how warriors worked. It was during the early stages of Luclin and was made by a person who played a female gnome warrior that was doing research on how the weapon damage bonuses worked and how AC worked by parsing themselves and guildmates getting hit and hitting with various bits of gear added or removed. Only thing I can remember about the forum is that it used a white background...super helpful I know.
Trying to find the forum post but it may be lost.