I shoot about 50 wild Roosters on federal wetlands every year. Without a doubt number 2 Steel is the way to go in a 12 gauge. Fours work pretty well too but picking the shot out can be a challenge. And you want to find them all or risk losing a tooth.
I also quit messing around other nontoxics and trying to get by with an older gun not meant for modern loads w/no company support. Bit the bullet and bought a 28" 12 CZ Upland sxs w/chokes and double triggers. Nice knowing there is a company that will fix it if it breaks (didn't this year). Sure...it ain't no LC Smith. But, its pretty dang nice and I can finally have fun shooting steel w/no worries.
I agree 100% buying quality modern gun is the way to go. When you look at pics of modern European hunters dressed in the field like people in US dress to Church they are shooting either modern O/U or Semi-Auto.