Still no pictures yet, but I got another look today.
What I thought was sleeving was just the way the crown was cut.
The sight does look like a Model 1 1873 with elevation markings.
I thought a true original 1868 had a more low profile rear sight.
Hopefully pictures are coming.
Well since you have not been able to post any photos, here are some you can compare it to:
• Rifle on the Bottom - Model 1865 Trapdoor, 1st Allin Conversion, Springfield, made 1865 with 5,000 model 1861s converted, used original barrel, .58-60 rim fire cal.
• Rifle on the Top - Model 1866 Trapdoor, 2nd Allin Conversion, Springfield, made 1867-1869 (1867) with 52,000 model 1863 type 2s converted (half were sold to European Nations for use in Franco-Prussian War – the remaining 26,000 were issued to US Army), more robust and simple action with original barrel drilled and sleeved from .58 to .50 cal., 50-70 center fire cal.
• Top Rifle - Model 1868 Trapdoor, Springfield, made 1869-1870 (1869), .50-70 cal., with suitable Civil War arms for conversion dwindling the 1868 was made new with some minor parts from Civil War arms used, reduced barrel length from 40” to 32-1/2”, approximately 52,000 were made.
• Bottom Rifle - Model 1870 Trapdoor, Springfield, made 1870-1871 (1870), .50-70 cal., a slightly modified version of the model 1868 (slightly longer action) and was essentially the control rifle all the others would be compared, Springfield made 1,020 rifles and 341 carbines for field trial.