Yes, 3/4" will work, but if you go higher you'll need 1" or the marine ply.
I've build several plywood tanks and that's all you need is the plywood and the resin. The biggest ply tank I have built is 72" x 28" x 24" x 3/4"or about 208gals.
The back, ends and bottom are solid ply , the front you just make a frame either doubled up ply or some hard wood and don't go thinner than 4". You can nail the pieces together, but screws are better. I used a powdered resin glue that you mix with water and that held pretty good.
When you are finished with the "frame" (the box) I used fiberglass cloth in the corners inside the box for a little more strength. I then poured in the resin mixture till it was about an 1/8" thick and let dry. I did this for all the surfaces except the top. The resin and fiberglass cloth are there to act as a liner "only" not much support, the plywood does that - don't let anyone else tell you that you need this or that, it works and I've done it.
The top is the PITA figuring out how to plan it so it won't block too much light.
For the glass, you lay the tank down on it's front, apply silicone made for aquariums on the inside of the "frame", slide your glass in (here you will need help) and get it positioned on the "face frame" then push down and just let the silicone ooze out. Place sand bags on top of the glass weighing it down and walk away for a day or two.
hth
