Good stuff Mark. This was a fantastic issue. Buckler essentially finished the plot lines in Defenders later on. He drew Astonishing Tales starting in 1974 so definitely before this.
Agree (again) with your analysis and opinion. I think, without looking it up, that Buckler started on FF around 72, and he was already a superstar in my mind when I found this book on the stands. It seems to me the character was never as good in later incarnations... but I probably need to do a reread!
Atlas Tales would have been the solution. They could have printed all those stories in one series. Atlas Two-In-One with main title and different title would have been too expensive to compete with Marvel.
The more I think about it, the more I like it. Start with those two anthologies and build from there. Also, as certain characters gained momentum, do a solo title a year or so down the road. No more than one new solo title per year. I believe such an approach would have led to more success.