I recall something written by a worker at Holland and Holland.
He said the American idea of keeping a shotgun "as built" is ridiculous.
Each Holland and Holland is made to order,to the customers tastes,and more importantly,to fit the customer.
Suppose,the eventof the original customer's death,another gentleman comes to possess the original Holland and Holland.To keep it original entirely misses the point.It makes the same sense as wearing the man's custom tailored suit...though he is only 20 lbs heavier and four inches shorter.
No.its time to adjust LOP,bend the stock,etc....And Holland and Holland would hope the customer would bring them the gun to have that done.
In regard to the Ithaca and other older shotguns:It was not built to run steel shot.Steep forcing cone,nature of the chokes,lack of chrome bore.
I'd find out the gentler -for -shotgun non-toxic loads .
Modern shotgun hulls have been cheapened.The brass on older shotgun hulls had a much better rim for the extractors to grab.
Ithas been my experience that the Ithaca struggles at times extracting cheap shells.Yes,the extractors can be optimized.Don't be surprised.
So the OP took an Ithaca that already had a ghastly Poly-choke pickle attached .The sin was already commited.No harm was done to the already altered barrel.M+P type short,cylinder bore shotguns are certainly one of the 37's variants.
So,no harm done.OP,there is a serial number range of very early 37's that will not accept interchangeable barrels.In the 70's,I could have told you.Check it out,and then its not hard to find an un altered original barrel on e-bay or elsewhere.Maybe $125 ,or less.Then you have a dual purpose outfit,change barrels in seconds.That IS a benefit if you get to go for pheasants!
Due to non-toxic shot,I'd go no tighter than mod choke,and best to have a long forcing cone cut.
Rather brilliant of you to buy a replacement stock to cut to the LOP that suits you.Shows respect for the originality of the gun,and you understand a shotgun must fit.
Well done,nice shotgun.
IMO,your critics owe you an apology.