Bob;
Yes I'm using L48-A4 from the AIM. As it's been explained to me, the 20 and the 45 on the page refer to 45 inches forward of the mating surface of the fender where it mounts to the firewall. The 20 is essentially 4.66 inches below the mounting surface where the fender bolts to the radiator support. If you refer to 11-13 B8 of the AIM you get a description of this, somewhat. The radiator support mount on the fender is listed as 24.66" (from the ground) so then 20 would be 4.66" lower than that if that makes sense. To make a long story short, I used this explanation and used a square and a dial caliper (yes I'm anal!) and the holes came out nice and straight, but about 3/4" above the body line. Not where they appear to be on original cars for the most part. I was extremely careful in my measurements, and they came out the same from the left to the right fenders, just much higher than I thought they should be. The result was 12 holes welded shut and more metal finishing to get the fenders smooth again!
The one car I've seen in person that I've taken measurements from only had one side that was reliable due to damage on the driver's side. Those measurements are basically what Charley has posted-I got 1" from the leading edge of the fender to the edge of the forward most "S" and 1/8" for measurement B and .2" for measurement C on the attached photo.
I've also read reports of questionable accuracy from the templates, so that was another reason for wanting to just do it by comparison. The hardest thing seems to be that the emblems are not parallel with the body line but I think I'll be able to work it out.
