Pete, sometimes finding a barrel within a few years of the gun you have should/might be easier than a later one.
As Tom Martiln has stated with L.C. Smiths, sometilmes you get lucky.
I was looking for an extra set for a hammer gun I bought that the barrels were cut from 30" to 25 3/16". They were now bore/bore. It shoots skeet very nice, but wanted longer barrels. I found a set of Grade 1 L. C. Smith barrels, 30" that had choke but not as described by seller. The hammer gun I had was a 1908, and these Grade 1 Damascus barrels were from 1899 and fit on gun with no work at all. I also had a pair of 26" barrels (verified by our records keeper to be just that)circa 1900 that also fit with no work, and fit another 1899 hammer gun. However, like Tom also stated, it took me hours to fit the for-end on the Grade 1.
I fit another set of barrels on a Zabala (American Arms-Derby) side lock 12 ga. double that had 26" barrels .004 and .012 choke with .718 and .722 bores. I bought an extra set from Numrich, and these barrels were not close to fitting. I spent many hours slowly filing, lamping, filing, taking measurements, etc. I got it very close but had to have the rim deepened. Had a local gunsmith do it for $25.00. I asked him what he would have done, he said either what I did or work on the hinge pin area of the barrel and the breech. I did do some on the barrel hinge pin, and the measurement came to the same as the fnished barrel, so I worked on the breech doing lamp black.
The gun closes up tight and the lever is more to the right. The barrels fit higher on the fences than the other by maybe a 1/64". These barrels are 27 1/2" and have mod/full choke. No proof marks.