I believe that the manufacturing capabilities of the day were pretty hit and miss when it came to holding tolerances.
The best way to find those would be to slug the individual rifle and go from there.
When they converted the Sharps 54 caliber carbines to 50-70 they only lined the barrels that were over 52 caliber! Under 52 they used as is! That tells you what kind of tolerances were held.
I know someone is importing a replica but that is all I know of it.
I believe any of the better restorers could fit a barrel for you.