Congratulations on a great piece.
I think I know who might of made it.
Twenty years ago ,give or take, I met a doctor in Florida that was a BIG shark fan and all around nice guy.
He had thousands of sharks teeth catalogued by size and species.Included in his collection was a cast of a prehistoric sharks jaw over six feet across.
He sold casts of teeth,jaw sets and of a shark head very much like yours to museums around the world.
I saw a complete casting in his shop with multiple rows of teeth,acrylic eyes and a great paint job.
Scared the hell out of me. I know the awe you must have felt when you first saw your piece.
I think he made several versions for different prices.
The fiberglass mold of the thing was HUGE...
Now this part is fuzzy so bear with me.
I believe he said it was a copy of a casting of THE shark, A shark or ONE of the sharks, caught in New Jersey during the summer that those people were killed in the attacks that inspired Jaws.
That's what I remember him saying.I make no claims to the authenticity of it.
I did help him make a fiberglass mold of a nine and a half foot great white that year that was caught not far from where I used to surf.
On a side note, the first shark fin I saw surface in the water while surfing was also the last time I went surfing.
Reguardless of it's possible history it's a great piece and I hope you enjoy it for a long time.
All the best,
Chuck...