I’ve had decent luck converting 3E era product into ACKS terms. I’ve been working on Red Hand of Doom off-and-on, getting it set up to use as a Domains At War event.
Since this particular Wilderlands take is using the 3E demographics, Aryxymaraki is totes correct in ease of conversion - dividing the settlement population by 5 gets you usually in the same ballpark as the source, and then just replace all the NPC levels and economic information with what ACKS tells you from there.
What you’ll want to look at after that is the map - I’ve never been able to deduce what 3E expected those urban settlements to survive on, and in general I’ve found they shoot for a much denser settlement pattern than ACKS default. For example, for RHoD, it’s a very small map, but there’s enough population in the valley depicted (which takes up perhaps 1/4-1/3 of the map) to spread over the entire map at the default density (depending on how you envassalate the smaller settlements). I’ve popped up to 650 fam/hex to get things to fit where they’re supposed to be.
Starting from the top down may be best. Take the City-State, pop 80K. In ACKS, that’s 16,000 families - surprisingly, a Large City; in this case we’d bump it up to at least a Metropolis. Assuming the minimum of 20K, a realm that supports the City-State is going to have 2 million families or more. You may or may not want to bump it up even more.
At the default ACKS assumptions, 300 families per hex, that’s 6,666 hexes, perhaps, a bit less depending on if you’re taking the urban population out of that 2 million before you divvy it up (which I believe is the correct thing to do anyway)
That may not make sense, even on the expansive Wilderlands map. What I’d end up doing is looking through the text (Hex 0620, for example, is mentioned as the westernmost point of the Overlord’s influence). Get an idea of the range of the Overlord’s realm, add up the families of the hexes he holds power/vassalage over, then adjust the demographics as required to get closer to the size of the hex area he’s supposed to have under his control.
Starting out at 300 fam/hex for 6,666 hexes, we can:
Centralized Settlement Pattern (pg 231) - Reversing the advice and going up two rows on the Realm/Domain Population column, we can say the City-State is part of a realm of a minimum of 500,000 families, taking us way down to 1,666 hexes.
Continuing from there, we can start increasing our population density (pg 230):
500 fam/hex: 1,000 hexes
550 fam/hex: 909 hexes
650 fam/hex: 769 hexes
which may or may not be starting to get down to a more reasonable number.
…Ballparking it, the first hex in that chapter is 0102, the last is 5231. That’s a range of…51 hexes by 29 hexes, or 1,479 hexes. Without actually studying the map, the above math got us down to 50% of that area, which may or may not work out in practice based on the terrain, water features, or vassaled settlement count, but I bet it’s a decent start.
This sounds like a lot of fun.
FWIW, Dwimmermount actually would hold some help here on how to present all this later - showing what I assume is the first look at an “ACKS Settlement Stat Block”.
It also (at 600 fam/hex) provides die roll ranges to randomize the number of unnamed domains and population of those domains for any given hex type - civilized, borderlands, or wilderness. I plan to deconstruct those later and redo my RHoD project in that same format. “Dynamic Domains and Lairs” is the title of the section, pg 60, I’m guessing this is a first glimpse at Lairs & Encounters and/or Auran Empire content.