A new barrel set up with open sights won't be much more expensive than modifying yours, and you'd still have a short bead sighted barrel of great utility.
One thing, most folks can do good work with a bead and slugs out to 50 yards with a bit of practice and training. A bead also is perhaps the fastest setup for close work.
Short barreled Big Four suffer from delusions. They think they're fancy quail and grouse guns and perform as such.
Run a few cases of shells through that thing before buying ANY accessory.