Went though that last spring on my 65. They make patch panel with the brace attached. Best to butt weld, and cut out the metal until does not rip. If you need a complete trunk floor side they also make them, but different than Chev. same for the gas tank supports. If I had to do it again I would get a 7 piece kit, not just patch panels. The problem is 64/5 are slightly different in the stamping. They have large oval holes on the front sides and a small hole in the center, and 66/7 have three large holes. Most of the replacement are 66/7 style.
