Greg,
If you could have the lab guys leave some of your escudo's "in situ" and letting them stay attached to a small piece of the encrustion in which they were attached to "being part of the cannon" that may increase their value...3x over...just a thought. *see attached photo
The picture (P1110391) where you see just a portion of the Bogota, is what I mean...just clean enough to expose full detail (side visible) but leave inside the encrustation and HELLO $$$$$$.
I'm smiling for you guys...congrats
Trez (Scott)