Looking through the box of spare bits for my new Ryujin II, you may need to source different standoffs for mounting your AIO. I know you're talking about the original Ryujin, not the II; but they are both standard Asetek AIOs in terms of the copper plate that sits on the CPU, the mounting stuff, and so on. They supplied 4 different types of motherboard standoffs with my one; original LGA 115X/1200/1366, Intel 1700, LGA 2011/2066, and AMD. The front and back plate that clamp it down onto the motherboard seem to be the same for all Intel, including the new 1700s.
There shouldn't be a problem with the size of the thermal interface with the CPU, the standard Asetek round copper plate is pretty big. LGA1700 is 37.5x45mm. AM4 is 40x40mm. It covers my AM4 CPU nicely, with plenty of spare copper. An extra 2.5mm either side (assuming the new Intel socket and cooler mount are concentric) will still be within the outer limit of the cooler plate. The Ryujin II 360 certainly seems to keep up with the cooling fairly well on my 5950X (running it at up to around 200W), so I'd expect the original Ryujin 360 to be competent at taming the latest Intel thermal generators if it's in good condition.
