It's not cheating if it's allowed.
However, Blizzard is changing things. Supposedly due to the Legacy mode the Karazhan farm is getting made impossible to use at the 70-80 range due to the rebalance.
But to get back to the forum topic: Just get it done as fast as possible. Check guides like the one in my sig, or follow youtube channels that specialize in leveling. It's doesn't actually not THAT long, even under 7.3.5's new scaling.