LOL,
Art, want a neat tip to find the center of the car easy? OK, I'll tell you anyway
Drop the windsheild in, you will see two small machined holes at the bottom of the windshield, find center and mark the body. There, you have dead center. If you use defroster vents, now is the time to cut them in too.
I have used measurements from what Don speaks of to as much as 11 1/2 inches wide at the front cowl, narrowing down to as little as 8 1/2.
I use 1/16th pin stripes with a 2" center.
DV...have at it fella! Sounds like your almost there!