Your current arm size is great for a tall guy who only weighs 220lbs. If you want size, you aren't going to find it in a 'spot inject'. If you were a pro weighing 280 with 6% and you were desperate to get another 1/4 of an inch, then I would say "sure, give it a try." But what you really need now are ass to the grass squats, bent over bb rows, bench press, dips, chins, deadlifts and some overhead pressing. Throw in some curls, closegrip press if you feel the urge, but don't go nuts.
Don't get caught up in the latest routine trends of the week, or what you read in mags. Just put together a solid routine built around basics. Keep with it. The only thing you need to worry about is adding some weight to the bar each week. Hell, even a 2llb metal collar, those little 2.5lb plates, etc. It doesn't matter, just increase it. It adds up over time. Also stuff your face. If you feel like you are eating enough now, you probably aren't. Eat, eat, eat, EAT!