Is the damage at the choke end or is there damage the whole length of the barrel? I would think old duck hunters would be the ones to ask, because of the damage steel did when it first came out.
I have a Model 37 too, not as old, that has a 18" cylinder barrel with a 2 3/4" chamber that I was thinking about drilling and tapping. I was going to try the Herter's 2 3/4" 1.5 oz. 9's load, because I don't need anything heavier.