Atari 800XL is a fabulous case to see, so I can imagine why you want to use it.
One serious point:
You have spend SO many hours on doing this right, why didn't you pay a little more attention to the looks? That DVD thing looks terrible (to me) and that I/O panel too. For a proto-type ok... but I'd say: do it again, but now nicely. It looks like my melted 'i had not time, and I really WANTED to make it NOW' CF-slot on the backside of my Atari 800XL. I did that with my Solder-Iron (what a terrible SMELL and SMOKE) ....
As somebody suggest, Im thinking in the pico PSU. With that on my hands I can improve my Atari PC. Until that happen is not more than a prototype, although a full operative prototype. .