Front end fit - or lack thereof...
 

Anyone have any tips for getting this stuff to line up? If I assemble the header panel and trim to the grille surrounds, everything fits together fine. It will not install on the car as a unit, and this is what happens when the pieces are installed individually. The screws attaching the grille surrounds to the lower reinforcement panel have been removed. Looks like I might have to bend the **** out of the header panel? It has to be repainted anyway.

Are the parts original or are they reproduction pieces?

All repops. The header panel is the only one I've found that fits the trim. Supposedly the surrounds are made in the original tooling.

Your issues are not uncommon with the reproduction pieces. I've seen other online posts where the reproduction pieces don't fit well together. You'll have to do some corrections to your header panel. Good thing it needs to be repainted anyway.

Yep, a lot of the repop sheet metal is more a general starting point somewhere between a flat piece of metal and the actual part they are supposed to be :)

Before you bend the header panel, find a original grille and try it. Something doesnt seem right with their height, but I could see how they fit with header off.

I know firebirds and have no idea how this nose attaches to the frame/car. But I would get back to zero and make sure all of the mounts, clips, hardware etc are correct. That looks to be off by way too much to be a problem of a repro part not be tooled correctly. I have seen some repro stuff that needs tweaked a bit but I think what you have going on is beyond that.

If you want to figure out how far off everything is and where the fault lies, try fitting some original moldings to the header panel and the surrounds individually. I was supplied an after market header panel for a customer's 67, and it was so far out of shape that I salvaged his damaged original header panel instead.

I had an older repop (probably 12-15 years ago)that was so bad I just threw it away!