Just to clarify, can you get it for $650 or $850? MSRP is $1,050, but you can get them for much less than that. I paid $820 for mine new. So if the $850 is what you'd be paying, I'd pass on it.
As far as the 45/70 goes, it would be a fun caliber. Mine is in 460 and it is a handful, but tolerable. I have not shot the 45/70 but it is supposed to have significantly less recoil than the 460's, 500's, etc.