Here's a photo to give you an idea of what's required to repair a botched installation of these brackets:
The side skins, corner brackets and all 4 lower longerons all have to be replaced to get rid of the bad holes.
Since I was also overhauling the engine, I took the opportunity to replace the firewall, engine mount (long legs now instead of the original short legs), and cowling.
The finished bracket installation looks like this when the gussets are incorporated:
Personally, I thought this was an enjoyable building challenge, but I needed the repair experience to support my long-term warbird aspirations. It took tons of time, though.