First off, just so you know, with that 3" long 410 chamber they are not known for 45 colt accuracy.
There is a reason shotguns have a smooth bore, they don't take to all that spinning nonsense. not and deliver good patterns anyhow. The plastic fouls the rifling terribly.
I have put sites on a number of shotgun barrels. Its not too difficult with some common sence, a drill press, taps and take tour time. If you have a machinists back ground, its a cake walk.
If not, its not something you want to foul up. Just take it to the gunsmith.
Good luck with your project.
CW