Saw this for sale over at the doublegunshop. Pretty good shape for a 50 year old cannon.
http://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=233437#Post233437
I'll bet you that baby would rock you shooting turkey loads out of it!
Having had a Spanish magnum 10 SxS, a NID Ithaca magnum 10 SxS, a SBE and an 835, the 10 SxS's were no worse than the 3.5" 12s, and probably better on the recoil because of the heavier weight of the SxS's.