Get a cereal box and cut it up. Now place holes onto cardboard that studs will line up with. Now trace emblem and cut along outside lines of shape. Now you have a template to place onto your project.
Everything I try to do like that comes up just a little bit crooked but I don’t notice till later. I already made a life size pic that I cut out and taped on the fender for placement. But I would like a template for the hole placement.
Only other suggestion would be this. See if an owner of the model car your working will allow you to take measurements and or place large sheet of paper and tracing key points.
An aluminum pie pan works nicely for the ones that really matter, you can dimple and drill the pin location then transfer to the location needed.
Scotty When I layed out the emblem holes on my 67 Nova I made a template off my friends' Nova. These are my NOS emblems so I know the stud spacing is correct but not positive how dead accurate the spacing is between the upper and lower emblems, it should be real close. Best mockup I could do, they are just sitting in place, not tight.
The assembly manual will show you how far apart they should be. What year are the flags from, I have a 63 Impala manual and a 68 Camaro manual.
Don't drill any holes. You can get very thin and very strong double sided tape specifically made for adhering automotive trim. For instance: https://www.amazon.com/Double-Sided-Adhesive-Automotive-Acrylic/dp/B01IHMK9G2
One trick I've used for emblems that have staggered pins, not squarely lined up, is to trace the outline on thin cardboard with big holes hogged out where the pins approximately sit. Cut that all out purdy. Then I use a leather punch with a multi-size head to make crisp, precise holes in small pieces of scrap cardboard. Then line up my templet with the back of the emblem, maybe hold it with tape, and then drop the scrap pieces with the holes over the pins and tape or glue them to the templet. The templet is now ready to be squared up where ever I want it on the bodywork and holes drilled.
I think the measurements from @DDDenny and various bits of wisdom from the others will work for what I’m doing. The fenders need to be re-sprayed anyway so I have some breathing room if I get em crooked.
I had a camaro recently that had crooked SS emblems, It bothered me every time I looked at. It was not my handy work tho.
Scotty These emblems were used on a number of Chevy models for at least three or four years. There are all kinds of templates being sold for this but my past research showed many inconsistant factory hole locations, you might as well just make it pleasing to your eyes. This won't really give you more information but here is some discussion on this very subject from the National Nostalgic Nova Association forum. https://www.stevesnovasite.com/forums/showthread.php?t=621578
Ive always put some whiteout on the tips of the studs and eyeball til its right .alcohol wipes for practice.
OK, now that things are more clearer. Add this to the mix of other replies you've absorbed. DDDenny's template is spot on to what I was making reference to. To get your horizontal holes dead on, get your rocker panels dead level using stacked material under your tires. Very important because using jack's at the wrong point of frame will only distort things. Use a small level along with template and level up the horizontal holes of template. No more "crooked".