Well got a bit more done. Came home tonight and thought I'd bite the bullet and start on my over flow before I chickened out and sat there looking at it for another week or two.
I really wanted to keep as much of the ABS frame as I could for strength purposes so I took a 2" hole saw and cut the plastic a bit further back then where I'll be cutting the glass. The took a Dremel with saw attachment and cut along the top of the glass from hole to hole.
So I'm really hoping that what remains of the top bracing will be enough for structural integrity. If anyone thinks I should add something to that side, speak up.
Here's what's left:
The red lines represent the edge of the holes that I'll be cutting in the glass. The holes will be 1 1/2" and I'll cut a line that just touched the bottom of those 2 holes. I know that I will not want any over cut so is there something anyone can recommend that I can throw on my Dremel or something that I can finish grind that little bit of break that I'll have in the corner?