Good timing. Hoping to get mine reinstalled this afternoon. Now, having said that, I cannot tell you that these are the original or correct fasteners, just the ones from mine that worked.
The screws into the brace appear to be #8 x 3/4" oval head stainless phillips.
There are also 2 bolts, one in the storage area, and one at the back under the cover where camaros have an ashtray/light. That looks to be phillips head 3/8" x 3/4" bolt.