I have shot a few of the somewhat older Marlin 45-70's and they shot fine. I've have not shot any made in the last 15 years or so. The Ruger #1's in 45-70 are a beast! You can pack the powder in those things. They can approach .458 Win loads(they do kick a bit when loaded hot with 500 grain bullets). Those Marlins with 300 or 350 grain bullets are fairly mild to shoot.
Times are tough - Keep your powder dry
"These are the times that try men's souls." - Thomas Paine