In general, any old double with such short (less than 27-28 inches) barrels and open chokes has been modified. "Excellent bores" in any old shotguns is cause for suspecion of having been reamed, maybe lots. That is why I have taken to requesting bore diameters, measured with a bore gauge. I doubt that you will get such information from this dealer. Proceed with much caution. Frankly, I would look elsewhere.
IF you are going to shot BP with card and fiber wads, be aware that in a bore reamed enough, the card and fiber wads will not seal well enough to give decently tight and even patterns, maybe not even for the undemanding CAS use. There MAY still be enough wall thickness for the guns to be "safe".
But, getting good patterns could well require modern one-peice plastic wads -- I have two such old hammer guns -- the sellers claimed not to know or suspect that the bores had been reamed lots. Both do shoot nice patterns with one-peice plastic wads and have been used heavily and successfully with such loads.
Niklas
