Ahhh no, actually it isn't. An FB/EK one is the same shape as FE/FC. It has the Holden lion, with the southern cross around it, with either a green or blue stars and a black background:
The EH one is the same image as FB/EK, but flat with a red background and black edge:
Sounds like what you've been offered is an FB/EK one. They fit, but upside down. You have to file the locating lug off to make it fit on an FE/FC horn ring.
A good condition FE/FC one is still nicer (see attached image)
Hope that helps,
RET