I currently own two Remington 1900's, and have previously owned two others.  The two I currenly own have both been restored.  Remember that any Remington 1894 or 1900 you see is at least a century old.
These Remington SxS's are well made, and relatively underpriced in today's marketplace.  Usually a bargain!  For whatever reason, perhaps "the name", they are not as treasured as Parker's or Fox's.  Most that I see are field grade guns -- maybe Remington didn't sell as many "graded models" as did Parker or Fox.
While many/most of the SxS 12 gauges have 2-9/16" chambers, there is ample metal for a competent gunsmith to open them up to the now standard 2-3/4" chamber.  Most seem to have been shipped from the N.Y. factory choked FULL & FULL.  Again, it is easy for a competent gunsmith to open the chokes to something more usable.
I hunt upland game with my Remington 1900's.  The 30" barrel has been rechambered to 2-3/4" and the right choke opened to IC; the left barrel is still FULL.  That makes a nice hunting combination for both phesant and quail.
             JERRY