The Spencer is a lever action rifle that loads thru the butt.
My recollection says that the "new" ones are only in 45 Colt.
The old one were 56-50s.
I just looked at Taylor's page and the "new" Spencers by Pedersoli are 56-50 or 45 Colt.
So whatever the 45-70 is it is not a Spencer.