It's not really to scale. I was just messing around with it to try it out.
The FREE piece of glass that my friend has for me is 72"x36"x1". I asked him if he has any that are longer, but haven't heard back from him yet. I was going to buy glass for the 6 tanks I was going to build before deciding to build this big tank, so I'm going to put a call in to see what 96"x36"x1" or 84"x36x1" will be. I'm sure something ridiculous.
The max that I can go with on the dining room viewing side is 96" since the fish room overlaps the dining room and kitchen.
If it is cost prohibitive, I'll build the front of the tank in such a way that it would be easy to swap out for 84" or 96" glass later on. Basically, remove the plywood, unscrew doubled up 2x6s then cut out the sheetrock and reframe the window.
I'm guessing the 84" piece will be around $725 and the 96" piece around $830.