Oops, missed your question. Wood putty to fill the holes then sand them down to be smooth. I will then put a layer of resin down over the whole inside of the tank. Once that dries, I'm going to use some heavy fiberglass along the seams and put another layer of resin over the entire tank. Once that dries, I'm going to do another layer of moderate fiberglass on the flat edges with a layer of resin over the entire tank. Once that dries, I'm going to put on a few more layers of resin until the insides are generally smooth. Once that's dried and cured for a bit, I'm going to install the glass, siliconed directly to the fiberglass. Once that's cured for about a week, I'm going to do a test fill. If it passes muster at that point, Its going to get two layers of the rubberized silicone pond liner stuff, can't remember the name right now. If it fails the first fill, I'll find the leak and fix it and lather, rinse repeat.
