I'd look for a used .44 a few years old on a SB2 frame, then you could add other high pressure barrels later. I've kinda always wanted a Mosin, but I really wouldn't know what to do with it. I already have a bunch of better rifles that aren't getting used enough. I know Dunham Sports has very nice ones refurbished at a very low price, and also has ammo for them. Bear in mind, the scope fitting is going to cost extra. You could also later ream the .44 to .445SM and shoot both. My .44 has the older over bored barrel. I just order .433 bullets from Montana Bullet Co. and load them myself. Even after it was reamed to Supermag, it still shot Hornady LeverEvolution ammo well.
In one very biased opinion, I'd go (have gone) with the Handi, SB1 or SB2.
Pete