XPS 8930 SE PSU and CPU cooler upgrade idea

There is a lot of space beneath the GPU where the empty hard drive bays sit. I want to hollow out the space and fit a new PSU. This would let me remove the swinging arm and then put in a nice big CPU cooler.  

Any reason this won't work or problems I could run into? The other option is obviously just buy a new case.

Im a CNC machinist so I have all the tools equipment and hardware necessary for any physical modification