Knowing what I know now, and IF I had had access to a competent sheet metal welder man for not much money, I would have had him fabricate a new lower bar for the radiator support, rather than replace the entire radiator support.
I have found pictures of this on the internet.
The rusty metal could have been cut away and new metal cut & welded to replace it, since 100% of the corrosion was on that lower bar, and nowhere else.
That way you would have fewer parts to remove from the support, and you wouldn't have to remove the tack welds on the top wings of the support, and wouldn't have to refasten these parts again.
Since I don't know any welders willing to work for free, I did what I did.