Overclockers UK have stock of the 645LT.
SFFLab will be getting theirs sometime in May, as they opted to only have their stock shipped by sea (where OCUK opted for airfreight on their initial batch, to bring it quickly to market).
Looks cool!
I imaging that regular tubes like the ones you've used are very hard to work with, without getting kinks! :-O
Love the color of the coolant, though
You might want to bleed it better, as others have mentioned. Also, please note that since the rad is aluminum and the coldplate is high-grade copper, you'll want to make sure coolant is fit for mixed metals - to avoid clogging in the coldplate and/or rad