FYI that's just a pump top/custom lower housing for the DDC, not a reservoir, which are a separate (and much bigger) part you add on. The top/housing is
62x63x63mm by itself, while the smallest res they offer increases the overall
height to 203mm. Only place I could see it fitting is lengthwise below the GPU, but I'm guessing there's not quite enough space for it (particularly once fittings are taken into account).
The Apogee Drive II won't fit, either.
@Wahaha360 picked one of these up recently to take some measurements, here it is with a 60 degree fitting (the ports swivel 30 degrees, so 60 degree fittings are needed to make it an even 90 degrees):
As you can see, it needs close to 70mm with these particular fittings (13mm OD Bitspowers).
@CircleTect has stated 51mm as the available CPU cooler/block height, so we're short by close to 20mm.
In terms of what might work,
Koolance has a DDC pump top, which can be combined with some
very short tube reservoirs. One of these might fit sideways under the PSU. Conveniently, they also provide models and drawings for many of their parts.
Another possibility is the
Fractal Design Celsius/
Kelvin expandable AIO. The only potential problem that I see, with the Celsius specifically, is the tubing comes straight out of the block, which might make it overall too tall to fit properly. It looks like it uses standard G1/4 ports, so you should be able to replace the stock fittings with right angle fittings, however that may not be enough to keep it under the 51mm maximum the case allows for.