Without completely redesigning the pistol, couldn't a custom (aka. expensive) slide be produced in order to eject cases to the left? I understand a different ejecting configuration would be required for this, but it should be less than completely remaking the pistol.
That being said, I don't see the point of doing this. Even for cosmetic reasons (as mentioned by the OP)... Sounds more like someone with far too much time (and not nearly enough money) on their hands. If it's just going to be a showpiece, then just get a shop to make a dummy slide, or block of metal that LOOKS like the 92fs but cannot fire/function as one. Solid magwell and a solid round for the barrel (maybe mock it up at the muzzle to make it look better) should satisfy ATF and keep it legal. Then again, it would be best to check with them BEFORE starting such a project. Or consult with a firearms lawyer.
I have no experience with the Beretta, but on most pistols, the ejector is on the left side of the frame. Also, most have the firing pin block on the right side of the frame and slide.
So, no, I think you need to modify the frame also.