@phanbuey
I built the case myself.
The case is a bit wider than a GPU is tall. The GPU(s) reside at the bottom, with the cooler facing downward (up to three slots wide). My main GPU is water cooled, so where the cooler would have been there is room to mount other things (like 3.5" HDDs or a second GPU (in addition to my main GPU, I've also got a low-end nVidia Quadro installed, which is why the PCIe x16 slot may not be degraded). The GPUs aren't slotted into the mainboard, but into PCIe slots that are mounted to the bottom-right side of the internal frame. On top the case holds a 2x140mm radiator, mounted above two 140mm fans. The mainboard is mounted vertically between the GPU and the top fans along the case's center axis (red line). A PCIe riser cable connects the GPU(s) to the mainboard. All cables are run behind the mainboard tray, where there is also room for four 2.5 drives (green lines), a pump and the reservoir. Front panel IO and power switch is in a cutout at the bottom front (I flat out stole the ncase M1 design).
The top fans pull air over the mainboard (on the left) and up between the 2.5" drives (on the right) and exhaust it through the radiator at the top.
Anyway, thanks for the help guys. I just wanted to be sure I wasn't hallucinating or missing something obvious.
@tabascosauz
I'm not too worried about upgradeability. As long as it does what I need it to do now I'm okay with buying something completely new in two or three years. For work I can use as many cores as I can get my hands on, which is why I would have preferred AMD over Intel, but the other two requirements are more important.