First off don't measure to the end of the fender, you want to know where the rad support is, not the end of the fender as that can change back and forth by moving them in or out or forward or back on the rad support right?
You want to use one of those fender bolts, that is if those bolts to into a fixed nut on the top of the rad support and I memory serves me they do. If they are going into a "j nut" that moves around to allow for alignment, you can't use them. You need a "control point" on that rad support on each side that is identical.
Cross measure from the rear bolt at the fire wall to the fender bolt on the rad support I just described. There is a bolt that goes straight down onto the top of the firewall right?
Is that area unmodified? We are still searching for "control points"!