Many ways to town, which road to take? A lot will depend on your tools available and personal skills. Me, I like a good challenge and do things the hard way on occasion..
Plus I have a kick shrinker here that has the dies that drop off (not flat across the face) so the radius would not be as much an issue. And since I can't weld as nicely as Bill, for some reason that option falls lower on my lean toward scale..
But in all fairness, as David Gardiner has pointed out many times, a weld seam in the case of a complex shape not only makes the job easier but also much quicker..
As Richard suggested, a slightly smaller flange (3/4"??) would be much less work than adding that extra bit to make it 1". So does it need to be that wide? Also, does the flange need to be bent in at a 90* or can it go higher than that? Higher up inside would require less shrinking overall.