The 2 3/4"inch is an older load and was used in more powerful guns like pigeon and fowlers. I know of no way to date a gun based on 2 3/4" chambering.
I prefer 2 1/2" guns left as found. However, a properly proofed 2 3/4" chambered gun is certainly not automatically rejected. The "trick" of shooting old guns is to keep pressure down and recoil down. This can be done easily with 2 3/4" hulls with proper factory loads or reloads. 2 3/4" chambers DO NOT automatically make a vintage gun suitable for SAAMI standard ammo.
