The XLR is designed to take full advantage of the LE ammo. Longer ranges need a different twist rate than found in the standard microgroove barrel and the longer barrel gives you max velocity out of the LE ammo.
Now, if long range out of a lever is your goal, another option might be a 308 Marlin Express. You'll shoot a 160 gr farther and flatter than the 30-30 will shoot the 140gr. Plus, Hornady has already announced the 140 gr monolithic FTX for the 308ME.
Bigsupplyshop.com has the 160 gr LE ammo for $18 a box.
You can get one with over $200 of upgrades (a WW trigger and big loop) from one of the members here:
FS 308MX with upgrades If I hadn't just spent money getting my truck fixed, I'd be telling you how that rifle shoots instead of pointing you to it