Springfield Cadet

I recently examined what appears to be a M1869 Springfield cadet rifle, 50 cal, no swivels, 1864 lock date, right barrel length. Two Questions.
It is fitted with a M1884 stamped beech block and appears to function OK. Were the 50-70 and 45-70 blocks inter operable?
Was the cadet rifle made in 50-70 or 50 US carbine?

According to my information, Springfield Cadet cartridge = Springfield Carbine cartridge, with case length 1.37" (a shortened 50-70 should work). Try a 50-70 case, and see how far it goes into the chamber!

Patrick