Hastings may have one in stock or could find one at
www.vintagesporting.com or
www.corsonsbarrels.com If you have a Gun Digest, hundreds of gunsmiths are listed in the back. They may have a website nowadays.
Here's what I used to do, when in business.
Cut the barrel back to remove the choke.
Re-crown.
Solder adjustable rifle sights onto barrel.
Re-blue barrel.
Sight it in.
If it has a rib, there are now adjustable sights that clamp on the rib.
Did this to dozens of barrels back in the 80's with great results.