I have seen them look fine on small bumper cars. Check out fan2488. His has the 73 front valence. I will admit, it helps that he has the foglights in there...
That valance looks nothing like a stock '73 front valance. Here is a better example of a stock '73 valance with a small bumper: No offense to the owner of that car, but it dosen't look right too me.
off hand i dont remember how far i closed it. i copied the radius on to sheetmetal then welded it wher i wanted it. i think i have some pictures of the back side.
Your car looks great! And I agree, if you are going small bumper, the stock '73 valance is not the best one to use.
I didn't know that the 73 opening was that wide. I have only seen fan's and assumed it was the original size (but now that he mentions it, I recall him telling me he slimmed it down a bit).
I think not running a front plate makes the valance appear pretty wide myself. The front plate sort of breaks it up.