Center the part in the opening there. The gaps are evened out at front, back and top/bottom of doors and same with hood although hood gaps can be bigger and still look good. Since hood overlaps grille to hide things or fudge them up to the eye then hood can go further back to look better there. I accept anything from 3/16" to up to 3/8" depending on where it is. Eye pleasing is good, or say both sides of hood the same or both doors the same. A lot of room for moving things around in there. The front fenders can moved backwards to tighten up any hole in door openings and the hood can be dropped lower to do the same. OEM measurement really means very little there.
The airspaces can move around after cars get jacked up in the air over and over, the unibody moves around some. Even simply driving the cars can move the unibody around, it is not rock solid and settles during use to be different from the day sold. Very common for hoods to say drift sideways to show the need for recentering after time.