Fjold,
As one left-hander to another, congratulations. I have a Baikal SxS in .45-70 and have had a ball with it. I did a lot of the work myself, but did have the triggers tuned by a professional. You have received a lot of good advice above, but I'd like to add a few things. When adjusting the barrels, move no more than a quarter turn. This sometimes made major changes for me. As a factory load, use the Hornady 325gr LeverRevolution ammo. It shot great for me.
Max