Generally speaking there were two model Sharps rifles and carbines during the Civil War muck like your Springfields. A model 1859 and model 1863. The only really noticeable difference was the deletion of the patch box on the stock and a change from brass to iron hardware. BUT - this was not a hard and fast rule because some 1863 models still had the patch boxes.
Interestingly, most pictures I have found of 1863 Sharps Rifles still have the patch box so in my opinion just do an 1859 version and the modeler can remove the patch box if an 1863 version is needed.
So I would suggest the model 1859 Sharps Carbine and model 1859 Sharps Rifle.
The ring & slide are on the carbine only for mounted troops
