I just did a little research and it appears a blue top was an option for 67's so your trim tag color code for Montreax Blue = D and the convertible top color for blue = 4. Since it's stated a blue and not teal as an option, I'd guess it's different than the 68's which is teal and matches the teal interior color offered. Maybe a better starting point is to match your top color to a blue interior for 67's?
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
