altering the gun in anyway, will reduce its collector value.

opening the chambers to 2 3/4" will reduce recoil when shooting modern shells. and it will help preserve the old wood, by lessening the chance of cracks.

keep your loads light and your screws tight.

I just finished unwrapping it, absolutely beautiful, excellent wood and sharp checkering, barrels perfect, one small ding on right barrel. All matching numbers, lots of case color hardening. How can I tell if has been rebuilt, because it certainly looks all original to me. Bluing on barrels is nearly perfect. She has 30 inch barrels. A true example of American craftsmanship. It fits together like a pocket watch, stiff on opening.

By the pictures you have provided us the gun appears to be in original condition.

The screws have obviously been turned (especially the one at the rear of the floor plate) but only show faint signs of turning.

one in the center bottom has been ruined, who can replace them?

nice original looking gun...enjoy.