Haaland is just not a good 9 for us. We need someone that presses like a mad dog and is really good in crosses (like a Dzeko that runs a lot). He can even be shit with his feet (I mean Haaland touches like 10 balls a game after all) as long as he is great at heading, positioning and presses a lot. He can be slow because with us it doesn't matter.
Or someone that is really mobile, great technique in small spaces, almost false 9 like (a Lautaro or a slightly better Gabriel Jesus).
The problem with Haaland is that he is really bad with headers, and his positioning in crosses is always the same, he is not that mobile outside of his runs. With space he is the best in the world, but we will never get that. We would have to change 5 players, and between changing 1 player or 5, I think the answer is pretty clear.