-- UPDATE --
Last gun show I was at, one guy had a small selection of gun parts. In a small zippered bag, he had triggers and it was marked "S&W K-frame triggers, $10" I looked 'em over and all were serrated
except one, so I pulled that one out and gave him $10 for it. Upon getting it home, it seemed MORE than obvious that I had something smaller than what I needed. I'd have to bet that I just purchased a J-frame trigger.
But no biggie, I have a buddy that already wants it.
90 minutes ago, however, I pulled a Model 10-7 of 1983 vintage out of the safe... one that I just don't shoot much. It's nickeled, four-inch, but with the standard tapered barrel. But it's got the smooth, thin trigger in it.
Snagged the 28-2 out of the safe also and went to work. I have been inside S&W revolvers once before, so it wasn't totally unfamiliar, but let's just say that I probably won't be filming for my own line of gunsmithing video tutorials.
When the dust had settled, I got
both revolvers back together after swapping their triggers. Both are 100% functional!
There is a side-nugget to report, and I'm
absolutely certain of this, it's not a guess: single action trigger break on the 28-2 is now
FAR more firm than before. Not a little. Not a deal breaker, just feels heavier than you'd expect from a 1974 S&W revolver.
And, as I suppose it should... single action break on the 10-7 is now
very LIGHT. As in, probably lighter than most of us would want on our guns.
As I've said before, I'm a double-action shooter, so I'm prepared to go forth with no care about it. But it's there, it's real. Others would
not accept how light it is.
Anyway, I appreciate all of the input in this thread and glad that I've come to a bit of a conclusion... with a happy ending.