At the moment I am thinking of having it in the lower section of the drive bays standing vertically - only issue with that is that the 320 cuts into the top drive bay - which means I either have to modify the current drive cage or get some different mounts for the hdd's.

Tubing is 3/8ID 5/8OD with 1/8 wall thickness - great tubing - using the same stuff in my own build so when disruptfam said he had some as well I just had to snatch it up!!