Well, I'm back to the post
I started to eat some crow, more or less. My car rolled off the line as a slant 6, factory AC car, but was converted to a 360/904 car at some point. I would have SWORN that when I measured that radiator, it was 22"...but I went out to do a little work on something else, and thought I'd measure again, especially the opening, bolt pattern, et cetera, after
@72bluNblu provided pictures and measurements. The radiator that was previously installed was, in fact, a 26", although whoever put it in did a sorry job of centering it. No matter. The lack of shroud made me think it was smaller, I guess. At any rate, I can confirm, that yes, it fits, but no, it wasn't a "drop in". Thanks to everyone who helped me, despite the fact that I could have helped myself if I had only double-checked my initial measurement. I wish I could blame it on something or someone else! I guess it's all part of getting older. :D
