NES cartridge dimensions
Below is a 2D drawing of an NES Cartridge PCB maximum dimensions, including holes and spacers.
NES Cartridge Outline
Here is a simplified outline of the above drawing.
(Source XDraft file same as above)
NES cartridge pin dimensions
Here is a diagram showing the pin dimensions and their pitch (spacing). Note: the pitch is 2.50 millimeters (0.0984 inches), not the standard 2.54 millimeters (0.100 inches) that is very common today for dual-inline package chips.
An NES Game Pak label measures roughly 55x97 mm, with the top 7 mm of that in the fold-over. But actual printing will need a bit of extra space for the bleed area. Here's a template showing the approximate size of a label for a standard NES cartridge.
acfrazier recommended printing cart labels on Avery 5164, Avery 5264, or Avery 8164 (4x3.33 in) labels.