If you want top ballistics out of the round, a 9" twist will be necessary for shooting the heavier 6.5 bullets.

A 26" bl. delivers up to 100fps higher speeds than a 24" using identical bullet weights.

The 6.5x68 usually out speeds the .264 Win. Mag by a small margin, given the same length barrels. That, AND the 6.5x68 doesn't have that useless belt - equated by some to mean power - the 68mm cases and many others do it without belts.
Seems to me, most 6.5x68 magazines hold 4 rounds, not 3 like the belted magnum cases.