i just did mine a couple of months ago on my '68. i coundn't find any templates or measurements for those emblems, only the arrowhead on the bumper and the 400 emblems on the hood. my holes were filled in with bondo, so the pre-existing holes were easy to find and drill from behind. i have no reason to believe that the holes aren't original, but there is a 1/2 inch difference from left to right side in the placement of the forward edge of the birds. the script logo holes are on the horizontal crease in the fender, with the bird emblem holes about a 1/8 inch higer (the emblems come out even, the studs are just not even to begin with). here's some pics of mine, maybe someone else could confirm or disprove my placements as correct.
from the forward edge of the fender, the right side bird starts at 3 inches, the script at 7 to 15 1/2, the left side is 3 1/2 and 7 1/2 to 16 inches. anyone else? i hope this helps!