Ironman;
I say go for it. With the .410 & 28 already you should have the hardest ones to find. You of course probably got lucky on finding a high condition 12. May be harder to find the rest in the condition of these three. A lot of these in the larger gauges at that point in time were used pretty heavy.
Outside of shotguns my other main collecting interest is antique & vintage sewing machines. My oldest to date is an 1862 Wheeler & Wilson.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra