Personally, I would leave the barrel alone.
I have this thing about old barrels, how made, the metallurgy and dimensions of yesteryear.
They will never make them old barrels again, and having run a Stan Baker Bore Diameter tool down barrels, I want the old barrels, and there is a point or two of constriction in most of those, even if marked cylinder bore.
I would keep the old barrel intact, it really is that good of a barrel.
I feel it is so much better than newer barrels.
I would get another barrel, with chokes, or have a qualified smith keep an eye out for a busted one (duck hunter fired it with mud for example) and have it done for external knurled chokes.
I prefer fixed chokes especially for serious use.
OLDer Cyl Bore and Modified are two barrels that are that good.
Yes, there is a short fixed mod barrel and that one is prized and folks wait years to get one.
I know one fella that waited years, and finally bought all he could afford when he found some.
Again, I want Choke, and I prefer fixed.
Those older Cyl bores, with the chamber, forcing cone, bore dia, and they did them , and they do have a smidgen of choke are that good.
That short fixed modified...yeah, some of us know something, we sure as heck do!