There is a lot of info online for identifying older wooden rocking horses, but I'm afraid I didn't have any luck finding information on identifying vintage fiberglass/plastic ones. Without a maker's name, it will be difficult. Have you checked everywhere under the belly, bottoms of the hooves etc? I'm surprised with the logo that it has that no manufacturer's name is on it.
It does look like a very high-quality horse for the time that it was made. If I'm not mistaken, it looks like natural horsehair was used for the mane and tail, which is something usually only found in carousel horses or very high-end ones.
He's a terrific little guy and quite a survivor for having come through a fire! I'm glad that you rescued him!