Custom barrel guidance needed

[Winchester50]

I'm looking to have a slug barrel (with rifle sights) made for a Winchester 50. My grandfather used it for bird hunting back in the day, and I'd like to use it for deer. Any recommendations for someone who can do this well?

I found Howard Montgomery online (https://www.turkeyshoot.net/GBG.htm) but don't know anything about his work.

Any guidance would be much appreciated.