The ECS ones are not too bad.
Marty unless they have changed them recently IMHO they aren't very close
First I must say that very very few of these paper (with no clear plastic covers) remain today. Weather and elements have taken their toll long ago on what was likely meant to be a temporary item.
Checked their current web page and noticed the following when comparing the one displayed there with originals
1- Color of ink used in different
2- Design (pattern of the printed pattern) is not correct for 67-68
3- The filled out information is from a 69 Dearborn decal - different from at least 67-68 San Jose and Dearborn
So other than the shape of the sticker and a couple of the details being similar
And of course (though as mentioned above not what you may want on a car being used) the material the sticker/decal is made from
Just my observations after thirty + years seeking original examples out