I'll tell you this, I wouldn't mount it in permanent till I had the front sheet metal on and stood back to look at it. I did all the same measuring on mine when I put the clip on. I trial fit the sheet metal and the wheel looked like it was back some. I'm talking VERY little but it looked like crap. I cut loose the clip (it was jsut tacked) and moved it forward about 1/2". It looks great now, and if there is anywhere you want it is forward too much, instead of back too much.
Some times the eye is more important than the measuring tape.
