2-3/4 inches or 70mm is the original Kodak width (which was slit to make 1-3/8 inch or 35mm) and I'm pretty sure 116/616 was this width too. The other dimension is however puzzling.
Are they individual negs or roll film? Because there were some tiny plate/cut film sizes too. And as Dwig says, 8-on-127 is another possibility, in which case one could argue that the actual images are about 40mm high and 60mm wide, but 60mm isn't 2-3/4 inches.
Can you give mm measurements?
Cheers,
R.