You mean like this ? You can use it. The "V" is slightly more on the 69 panel. I picked a cheap one up from Unlimited Products purely for fitting. If you are keeping the Firebird bumper and not shaving it, then you will have to trim the valence to fit. Fiberglass is a lot easier to play with than metal. See attached.
Glad you like the frontend. We went through something like 100 photoshop renderings before Kris got a hold of it and worked his magic to come up with the final look. If you saw all of the hood/grille/bumper/valence/light/stripe combinations you would laugh...