Hi Dave. The headlight bars I have looked at were approximately 1 3/4" forward of the vertical edge of the shell to the back of the bar. Mine is set 3/8" further forward. I didn't have the insert to use for mock up at the time, so I gave mine a little more gap. It will be best to have the insert in the shell when you set your light bar.The shell will need to be in it's correct location and the fenders will need to be mounted with running boards and fender braces bolted in place. My fender braces had to be modified to work. This was a very time consuming job to say the least. I'm sure some of the guys that have built several cars can jump in and help you with this. Take you time here. Hope this helps