Okay...here is the replacement rib. Since I was starting from scratch, I decided to just bend the forward flange the opposite way from the get-go.

Hrm...if I have flanges pointing opposing directions, the rib won't fit into the brake to bend the adjacent flanges.

So, off comes the forward flange.

Notched out the bottom of the aft flange to accomodate the slight bend in the sub panel.

Trimming the top flange to 5/8 wide. Note...if you're having difficulty making nice cuts with snips, there are a couple bits of technique that facilitate good results:

Bottom flange formed and part clamped into position.

Match drilled this flange through the (already existing) holes in the sub panel.

Positioned and drilled the forward flange.

Since this flange is narrow, I decided to use 3/32 rivets. Why are there so many rivets in this piece, you ask? Here's what happened...I calculated earlier that 12 3/32" rivets are needed to provide the same shear strength as five 1/8" rivets. However, when I was laying out this pattern I mis-remembered that I needed 9 rivets instead of 12. After drilling those 9, I realized my mistake and decided to just drill another 8 rivets in between those. So, yeah...17 rivets. Sigh.

Positioned the foward flange and taped it to the little plate on the aft surface of the firewall.

Then match drilled and dimpled the two pieces. That's it for the day.