What size ghost did you use on your 220?As long as you've confirmed the back glass isn't tempered, it's pretty easy. Key with drilling is to be patient, keep the drill bit wet/cool, and take it extremely slow. I was extremely nervous but it went smoothly. I drilled the back of my 60 cube once upon a time as well without issue. Do you have a LFS nearby? They may be willing to drill it for a small fee. Transporting a 180 isn't ever fun though.

