I would be a bit concerned about the acrylic thickness. 3/4" is a little thin in my opinion and will deflect or bow out. My tank is 96x48x24 and I went with 1.25" thick front and back and 1" on the sides top and bottom. Also, regarding the top, depending on the bracing, that could be a concern as well. I have 2 24"x24" openings and have some deflection in my top which is 1" material. Granted my tank is now around 17 years old.
Can you post any pictures of the tank you are considering?