I've got an M8 2.5 on my #1 (I know, not a Marlin), but I have thought for a while, one of those SWFA 1-4 AR scopes might be REALLY cool on a .45-70.
Mil turrets and reticle, illuminated. Looks handy close in, at low light, and dialing a 400 grainer in from way out there would have to be a ball!