if everything is operational, be it 8 or 10, can it be restored rather than parted out?

At which end of the barrels did you get the .835 measurement? What is the diameter of the "other" end? What is the exact distance between the firing pin holes, center to center in sixteenth of an inch? If there is any further question, we can mail you an eight gauge shell casing for you to try for fit in the chamber and post a picture. Your gun should not be parted out. You can get way more money for the whole thing than any sum of parts. Where are you located? We can send you to someone to check your gun out.

Okay,
I really messed up; the 8 on the barrel end was part of the weight stamp (5 8-- as in five pounds eight ounces).
Sorry for the confusion.
It is a "Twist" Damacus barrel, 10 gauge, hammer, built in 1885, all components in operational condition ( now cleaned and oiled by me--- although not sure I can reassemble to the working order as found?)
They are 32 inch barrels, measure .850 at muzzle , .750 at barrel end, .060 thickness of steel at barrel end.
Might continue to clean, repair stock, reassemble, and make a nice wall hanger?
Might part out?
Into it pretty cheap, so a nice wall hanger is where I am think now.

Don't part it out! Send it to Turnbull to fix. I did it with a 10 ga. on a #6 frame years ago, Turnbull said they could barely rehab it. It came back a work of art and a great shooter. Back on line where it belongs. I've shot a lot of geese and ducks with it, almost exclusively with black powder shells.
Good luck!