1. Hunter Arms' engineering drawings from 1907 on show .728 - .729" to be the standard 12g bore
2. It is not uncommon to find turn-of-the-century bores (presumed original) of .729 - .732".
3. I would suggest confirmation of your findings with another bore gauge.
4. A good "look" at the bore requires direct visualization with a bore scope.
5. Honing is entirely dependent on wall thickness (and the expertise of the smith!) and will make cleaning easier. It will do nothing for the recoil or pattern; other than tighten the pattern if the choke is not also relieved.
6. IF you do have a barrel specialist hone the barrels, it is my opinion (and others certainly will disagree) that lengthening the forcing cone to 1 1/2" or so would be reasonable. Doing so will do nothing to diminish recoil, but might improve the patterns.
Because the angle of the cones is greater than the external taper of the barrel, wall thickness is usually greater in 12g at the cones compared to the end of the chamber. This may not apply to small gauge barrels.