John: if the seller is unwilling or unable to provide meaningful numbers (end of chamber, 9" from breech, and 9" from muzzle) I would do exactly what you mentioned in another post; have it shipped to a doublegun specialist for an immediate inspection. The expense will be well worth it if the barrels are found to be unusable. The right barrel has very likely been honed, and you cannot know what other mischief has taken place.