Some of the older Ithacas were "hand fitted" to a degree and barrels sometimes will not be simply interchangeable. Here is the shop for the old head gunsmith from Ithaca before they moved the business to here in Ohio
Sometimes you can find the old original Ithaca slug barrels for not much. BE ADVISED that they were made undersized for the Remington slugs that were available then (I cannot tell you the exact timeframe).
My older one came as a set, vent ribbed, tapped for chokes, field barrel and rifle sighted slug barrel. I had the gunsmith that I deal with ream the barrel out to correct 12 gauge size and will accomodate slugs and sabots (even being a smoothbore) without excessive pressure. It's basic function is a home defense barrel as the length is just perfect.
I might even try it for close quarters rabbit hunting in the brush, might be just perfect for that.
I have 2 12 gauge Ithaca field guns and 2 Deerslayers with the screwed in barrels. They are superb guns.
Don't go chopping it up. You might find out you want to go upland game hunting and it will serve you very well in that regard.