I have 4 Marlin 336's all with scopes. One has an old Burris 4x, one has a Leupold VariX II 3-9, one has a Leupold VX II 2-7, and my favorite hunting gun has a Zeiss Conquest 3-9. I personally hate see-thru ring, but to each his own. There is alot of Marlin owners that view scoping a 336 as a cardinal sin, but for me to shoot past 25-30 yards, it is a must.
I want to recommend trying the Hornady LeverEvolution ammo in your new 30-30. I have gotten super accuracy on targets and great terminal performance on game.