Bullet drop really doesn't matter, as long as your scope has enough range of adjustment to handle it. At 600yds most scopes will have plenty. You're shooting a known distance (KD) range - once you're dialed in the elevation doesn't really vary outside of minor changes due to lighting or up/down drafts. If you assumed the same load would be running a hundred or maybe one-fifty feet per second faster out of a longer barrel... there might be some decreased wind drift with the faster load/ longer barrel, but thats about it - and as swd mentioned, not a whole heck of a lot.
If you are new to the sport, I'd say take the gun and get out there and shoot. Go to a match or three before making any decisions on gear. A lot more of this sport, especially F/TR, is about what goes on between the Peltors with regard to reading the wind than it is about the equipment. Down the road, after a couple thousand or so rounds down *this* barrel, get a new tube thats a little longer and with a faster twist (1-7") - you'll likely see more benefit from a faster twist barrel and heavier bullets than just a longer barrel with the same twist rate. Even then... its not like its gonna be easy. The F/TR class is inherently handicapped by caliber (part of the fun for most of us); trigger time is about the only way to work past that.
