Yah, I'd make an effort to repair it if you have enough of the pieces to make it structurally sound. Two-part epoxy would be my choice, too.
Once glued together, if there are some gaps, they can be filled with bondo. Then you can sand as needed and repaint.
Casting a reproduction is not rocket science, but it requires an intact original to make the mold. If you repair your ring well enough to serve as the model for making a mold, then presumably it's repaired well enough to use. An alternative would be to fabricate an entirely new model out of clay or whatever, which exactly matches the original, and use that as the model.
I have made simple one-piece molds in the past. This thing might require a two-piece mold. It's also a rather large object. Neither factor makes reproduction impossible, but they would make it more complicated.
Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html