I believe that the leverevolution ammo is your answer. You don't neede the XLR to use this round. You can get 200 yards out of any 30-30 with this ammo in any gun, the XLR can get you out to 300 with a little practice. I just bought the Marlin 336SS to use this round in. I don't know if it makes a difference but the XLR has a 1:12" twist rate and the regular 336SS has a 1:10" twist rate. The slower rate is all that the 160 grain leverevolution ammo needs but it might not be fast enough for a 170 grain round nose bullet.
You have to love the looks of the Marlin in stainless steel, here's mine.