They sell them at many of the big box stores. The most accurate screws and fasteners that I've found are at Heartbeat City Camaro. The ones at Firebird Central and Classic Industries are not as close to the originals but will work. Maybe it's becoming apparent, but I have a lot of unused parts from this addition....
1968 Pontiac Firebird 400 Convertible - April Gold/Deluxe Black Automatic 1968 Pontiac Firebird 400 Coupe - Aegena Blue/Standard Teal 4 speed 1968 Pontiac Firebird 400 H.O. Convertible - Alpine Blue/Deluxe Teal Automatic 1968 Pontiac Firebird 400 Coupe - Autumn Bronze/Deluxe White 4 speed