The rear bumper brackets are bent, rusty and one of the bolt threads is unfixable. Because of this I decided to order some new ones from VP-Autoparts. I need to wait for them to arrive before I weld in the trunk floor bumper braces as I need to ensure everything lines up. Thankfully the bumper itself is good.
The new brackets fit well and I was able to fit the bumper back onto the car once the valance had been installed and painted.