I had the SAME " GAP " with the front bumper of my 1970 El Camino.
I was ready to cut ,,shim,,play with,, or Do what ever to center my front bumper and have it EVEN on each side.
After talking to a smart body man ( I was driving it, One thing left install the Front bumper)
HOW DID I CORRECT MY SCREW UP????? Remove the fenders and hood, Grill, Etc.
NOW most important...Get the body bolts loose,,, SQUARE the BODY to the frame! Get your rule and start measuring. When the body is on the frame SQUARE, EVERYTHING will fit.
Your manual will tell you how. Many simple tricks to get the body in the correct position. YEP, You can/do shortcuts. I did not want to go that route. I wasted two days and used a lot of very bad language. The end result the car is 100% correct and perfect. Bottom line,,,,,, I was the dumb AZZ who set the body on and said............ LOOKS GOOD TO ME !
Drivers side " Bumper dam near touching fender,, Pass. side about a 3/4"-1" Gap ???? "
.......... Time for the yardstick!
If what I did sounds like a lot of work, ( It is a lot of work) I would ask for a 2nd & a 3rd opinion from some other folks.