My new system is work-in-progress since early May 2024, that is: Dan Case A4-H2O, with a side-mounted 280 mm AIO and a top-mounted GPU.

Currently I’m using a Gigabyte Radeon RX 6800 Gaming OC, which is 286 mm long, up to 58 mm tall and officially only 115 mm wide.
Also weights about half a ton (kidding, 1.3 kg), lovingly called The Brick. Its chonky, unwieldy and vastly inflexible in montage, esp. when wiggled inside the radiator compartment of the A4-H2O.

Rest of the specs and overall progress is found over at the SFF.Net build log: https://smallformfactor.net/forum/threads/portable-workstation-a4-h2o-w-280-radiator.19558/

Image dump as follows:

280 AIO test install

Initial test fitting of the 280 AIO radiator, right after the case arrived.

Second test ftting:

Secondary thorough building with the 280 radiator, including trying to figure out how to route tubes etc.

Test fitting of the GPU

First try with fitting the GPU on top. Last picture showing the painfully bent riser cable.

Rotated GPU test fit

Second try with the GPU rotated by 180°, ie. with the fans pointing inside of the case.