Does anyone know of a buisness that will take, for example, an old Leupold 3x and upgrade to coated glass, gas them and change the finish to flat? Thanks.

I know of no one who would do the glass upgrade. That would be a tough order to fill.
Leupold has a lifetime warranty on all of their scopes, but I doubt that they would have any glass they could coat and install for the 3x. Those scopes are old and I doubt that they could help you, although it might be worth a call to them to check it out.