Building in a 12.6L case was definitely a challenge, but I'm glad I took it on. Biggest obstacles were having to saw and file brackets and screws to mount the reservoir onto the side of the case as well as finding a cpu block that wasn't obstructed by the capacitors on this motherboard. I also had to remove the front IO ports to make room for the rad which isn't ideal, but it's necessary if you want to use the Ncase with a window.
For anyone planning on using the z390-i, make sure you choose a "smaller" cpu block because those capacitors (left side) are taller than the cpu socket; I had to replace my motherboard after screwing down the cpu block and damaging those parts.
The Ncase is really versatile, it was a tight squeeze as was expected, but I was pleasantly surprised by how much I could fit in there. The case's air flow is impressive too, many people told me a single slim 240mm rad wouldn't be enough for a full loop but it definitely is; the cooling is probably also a testament to just how good those Noctua fans are (definitely worth the brown colours!). I definitely need some custom cables because the back right is a mess, i'm also waiting for two low profile 8 pin gpu connectors to clean up the front of the gpu.
If anyone has any questions or is planning a similar build, please don't hesitate to ask.