Wow, thats a rats nest of a case.
And as for the remount question: Don't worry about draining, the clamps should hold it just fine. The main point of the remount is (for me at least) a reapplication of TIM and to hopefully get better surface contact with the IHS.
Complete chaos in there.
But since I am replacing fans, and perhaps even moving WC components around I didnt feel it necessary to tidy anything up yet. Ill take care of that later and when Im done, you wont believe its a working computer because you wont be able to find a single wire
(well, close to that anyhow hehe)