Awesome build luke.

I've been using an A70B with quad GTX's and ran into the exact same problem with the PSU to close to the bottom slot

Managed a workaround when I was using GTX295's (see avatar) and am currently working a rethink on thre 470's and a 480 in the same rig.

No where near your skills in terms of beautification, I tend to play lip service to beauty and go for clear airflow and stuff all the cables round the back

But again your PSU mod is exactly what I may have to do if I run into trouble, unfortunately the mod might be more dramatic as the A70 doesn't have the fan holes in the bottom so I'd have to cut my own.

Again fantastic build.