So the prices in 5e for many things mostly match up to ACKS prices well.
The big disrepancy is that you level up much faster in 5e, i.ow. there is much lower amount of xp required to advance in level.
ACKS' economy is based on the idea that a level 10 fighter has found, and at one point or another owned, a certain amount of gold pieces worth of treasure.
So there are three ways of matching it up. All of these assume that the player side more or less uses 5e but the DM has made a world using rules similar to ACKS.
1. Increasing the wealth by level
1a. Remove xp for monsters, give out 1 xp for every 5 GP (instead of for every 1 gp). The xp requirements in ACKS are on average about 5 times higher.
1b. OR, instead, change the XP advancement curves to be similar to ACKS.
2. Keeping the wealth by level
1a. Remove xp for monsters, give out 1 xp for every 1 gp.
1b. OR, just be diligent about handing out tier-appropriate treasure according to the rates in the 5e DMG, that generally match up pretty well to one gp per xp.
Now, if you do option 2, then you also need to change when all the level-based titles, followers, castles, rulers etc show up. Base it on xp instead of level. In other words, an ACKS fighter can get a castle, followers etc at 250000 xp. That's the equivalent of a level 17 fighter in 5e. In other words the domain game gets postponed. The levels of various rulers similarly get changed. The "Demographics of Leveled Characters" table on p 235 change. The level in ACKS that only 1 in 3000 can aspire to is 6, and they are possibly the ruler of a march or large town. In 5e that almost a level 8 character.
So option 1 games (either variant) will have weaker rulers, weaker and more mortal characters overall, a slower and a more down-to-earth pace. Option 2 games (either variant) will have faster leveling for non-domain things but same pace for the domain game, it'll have more mighty heroes and rulers with more HP, more spells more everything.
(I'm not here to advocate for any particular one of these four (1a, 1b, 2a, 2b) solutions -- generally I think option 1a is a little easier than 1b since then the players can still keep their 5e and Dungeonesque PHBs, if you're doing option 1. If you're doing option 2 then it's up to you.)
Also, for those who do option 2. These two tables might help:
For seeing what 5e level a certain ACKS ruler might be:
(The whole boons thing in 5e is pretty crappy; only 30000 xp per boon? But that's what you earn in a day at that level. Feel free to replace that part with something else.)
|ACKS level (avg of f/t/m/c)||5e equivalent|
|11||20 + three boons|
|12||20 + seven boons|
|13||20 + eleven boons|
|14||20 + fifteen boons|
For seeing what ACKS stuff a character at a certain 5e level might get:
|5e level||ACKS fighter||ACKS thief||ACKS cleric||ACKS mage|
In summary, option 1 games will feel more like OSR games. Weak characters, slow progress. I like it♥
Option 2 might be good for those who already have a very 5e:ish campaign underway and are looking to bolt some ACKSiness onto it.