We added more speaker options to our dash bracket, you can know get the bracket with Pioneer, Kenwood or Rockford Fosgate speakers installed. All 3 have been installed in a car to verify fit. On a AC car the duct work can make the job frustrating but the new speaker set up is actually smaller than the original so that helps some.
1st gen Camaro/Firebird dash speakers at the link below:
https://screamingchicken.com/speakers-1st/
2nd gen Camaro/Firebird dash speakers at the link below:
https://screamingchicken.com/speakers-2nd/