Siegel sale 1150 has a nice group of the kings of the US coils (my opinion) the experimental gov't issue of 1908, all authenticated:

That bottom strip has the paste-up and joint line.
Could these be what you're looking for? If so, you will need to dig deep.
Forgot to mention that this sale is coming up on March 1. You might still be able to arrange financing. Cat on the 1c vertical coil is now 335,000. I remember when it was 16,000, back when I was trying to do a specialized study of the 1c series 1902. Ha! It was as far out of reach for me then as it is now.