'73-'76 Front license plate mounting
I recently went through this exact thing with my 73, and found that there is a big heavy ugly metal bracket that goes on there to mount the plate on.
I couldn't put that ugly POS on the front of my car, so I put the bolts through the center of the plate after the frame was bolted to it and painted them to match the color around them.
The OEM bracket also makes the plate stick out from the bumper, and I didn't like that either.
I can take a pic of the finished mounting if you want.
Here ya go.
You can see a bit of the black bolt head but the white one is pretty much invisible.