The correct label for that era (main label) would have likely measured:
8-5/8" wide by 7-1/2" tall.
The label would have featured the Lancaster coat of arms and at the bottom of the label "Inventor".
Typically, there would be three smaller labels included as well. A "shot charge card" would be a label roughly 5" tall x 3.5" wide that would specify the amount of Curtiss and Harvey powder to use with the gun.
An additional label in orange lettering was about 2-3/4" tall by 4-1/4" wide entitled "Hammerless Guns".
Lastly, there was a label of about 4-1/2" tall by 5" wide in orange ink that had a schematic on it entitled "Ejector Hammers on Forend". The brief description then explains how to prepare the forend to be attached to the barreled action during assembly.
Here is a visual example of the primary maker's label, albeit the reproduction is sized down considerably:
Here's a pretty good example of an original from your gun's era as well (note the small label to the right "Hammerless Guns" also):
