I did this to a GLASS 40g breeder and it's been running fine for 5+ years (no leaks, cracks). I had my local glass shop cut me two long strips of 2 inch wide glass (1/4"' thick) and ran them across the length of the tank, one on each end. Silicone and clamps for a couple of days.
As far as the removal of the black brace it's a major pain in the a**. I used a fine saw and separated the perpendiculars. Then bent them with my fingers to snap the sides off. Finally, I slowly ripped off the top pieces. The biggest pain was cleaning all of the old silicone off and getting it ready for the euro brace. Mind you, the glass might not be perfectly level and flush when you take the black plastic off. I got lucky and it was. Also, I didn't add a center brace.