All the waterblocks I have put together are based on either K6 heatsinks or (1) P100 Heatsink. The CPU stays under 100 F under heavy load. But yeah, you could just go ahead and wrap up some heatsink(an milled down copper inlayed Alpha would proably be best for the newer AMDs) and build a casing around it. You'd proably want to mill it down to a size the size of the Socket or slight larger/smaller. And proably a lower height as well.
------------------
Watercooled K6-2 450 at 600