A pair of GH 16g. guns that I finished last year for a customer.
He wanted Ruffed Grouse on the bottom of one and dancing Sharptail Grouse on the bottom of the other. The frame engraving needed recutting after polishing, so Gournet added Fanned tails to the birds of the one and the other needed a lot more polishing and the bottom scene got wiped out completely so putting the sharptails on was no issue.
IMG_5167.jpeg
I posted this because this is kind of an example of what you want done. And I fully understand why you would want to do it. To make a GHE that is YOURS and special. And it truly would make a killer looking gun for sure.
Either way, what you want done could be done with an original G grade or as an upgrade. Either way.
And may I offer the piece of advice and make sure you work in the right order on this. Don't start with the engraver. Work with a good "general contractor" that would do either all of the work themselves, or a lot of the work in house and then coordinate the whole project appropriately the way it should be.
I see too many examples of owners piece-mealing out the work themselves or starting with the engraver for an upgrade project. And the results usually end up less than desirable.