I don't play the modern (post-2017) Necromunda, so I could be wrong about this. But, that said, he's what I think...
Gangs of the Underhive is basically obsolete now, having been replaced by the House of... books. So, it isn't designed to be paired with the 2023 core book. It might work, but there might be things that don't fit neatly. (Be prepared for that anyway!)
If you have access to the 2018 book + Gangs of the Underhive, then (I assume) you could simply play the game as it was in 2018. But you wouldn't be on the most up to date edition. That shouldn't really be a problem, but it might be an issue if you did ever want to play with other people outside your group.
p.s. You could try looking (or re-posting) in this thread:
yaktribe.games
Gangs of the Underhive is basically obsolete now, having been replaced by the House of... books. So, it isn't designed to be paired with the 2023 core book. It might work, but there might be things that don't fit neatly. (Be prepared for that anyway!)
If you have access to the 2018 book + Gangs of the Underhive, then (I assume) you could simply play the game as it was in 2018. But you wouldn't be on the most up to date edition. That shouldn't really be a problem, but it might be an issue if you did ever want to play with other people outside your group.
p.s. You could try looking (or re-posting) in this thread:
N18 - Beginners Question Box
Dont know where to start? Dont know which books to buy? Is the Starter set worth buying? As far as Necromunda rules go, there is no such thing as a stupid question, so ask away! FAQ:

