Out to 500 yards, you will not notice the difference between a 22 inch to 28 inch barrel for accuracy. Muzzle velocity will improve for the longer barrels, with the biggest bang for the inch somewhere around the 24-26" mark for the '06 case, but overall accuracy won't really be as effected by the barrel length itself.

That said, a 26" pencil barrel may actually flex moreso than a shorter, relatively stiffer barrel. Cutting a longer barrel dictates that you need a bit more barrel diameter at the shank especially.