I went ahead and ordered a Gigabyte Aorus 1080 Ti Waterforce WB from Newegg, along with an EVGA 1600 T2 PSU.
The Aorus has the most aggressive stock clocks of any of the currently available waterblocked 1080 Tis. I like the EVGA Hydrocopper as well, but they're out of stock everywhere except Ebay... where they're $1250.
The T2 series are phenomenal PSUs. Even if I go with the 7980XE and push it into the upper 4s, a 1200W would be enough, but I decided to go for a little extra.
My inspiration for this build is the old cases used by VoodooPC... I used to want one of these back in 2002 or so: