Awesome that you can enjoy the car now.
A few firebird owners here in AZ have been having the same problems and having the AC cranking when it's 100+ weather only makes the coolant temp creep up more.
Friend with a 67 installed a champion radiator with the factory shroud and 7 blade fan and heavy duty Hayden clutch and he can cruise all day long with the AC on and not go over 185.