I would go to Ithaca section on http://www.shotgunworld.com/bbs/viewforum.php?f=59and post your questions.

These guys should be all over this question, and you will get all your options.

I believeyou'd be better off buying a new shotgun and leaving your current gun alone. For a gun that age, barrels would have to be hand fit, and choke tubes would not be an option. Based on cost and availability of barrels, you could get a new gun for the price. Those 16's are pretty desirable guns, so I would think you could easily sell it if you wanted to.

I personally would keep it as is.

KJ