I second the 7/16 tubing. And please don't put those hose clamps on your loop - they're hideous! If you use 7/16 tubing, hose clamps aren't even necessary - though I would probably still use them anyway for peace of mind. Use something like this instead.
Also take a look at the Koolance CPU-370 block. It's a bit more expensive, but it's supposed to be the latest and greatest and supposedly it has a top-notch mounting system.