While reading through old AK logs, I discovered that Vex Thal and HoHonorB both had 600 radius ignore distances, so 600 might have been commonly used way back then for many zones even if some zones may have been reduced to 600. (or perhaps memory is faulty and they were always 600)

AK had a bugged bard bellow ability that was usable from unlimited range and ignored LoS. I discovered log chat of a bard attempting to use this to pull NPCs from across the two zones. Knowing where they were standing (mentioned in the chat) and the described behavior of the pulled NPCs and measuring the distance allows me to know with a very high confidence.

I have a large correction to make here: low health aggro is based on CURRENT hitpoints and not maximum hitpoints. I.e. it shrinks as the mob nears death. This was a large oversight on my part.

Also I noticed that low HP aggro starts at <25% not <20%.

I can now say with a high degree of confidence that PoFire and BoThunder were also 600 ignore range back in 2002, so it's likely all PoP zones were

I came into EQ in the (late) PoP era. I don't how many times it came across group chat, (with too much aggro) "ZONE! ZONE! ZONE!" lol (fun times). Some of us had hotkeys for stuff like that.