^ Nice! But think twice about getting a Gitzo ballhead. They make great tripods but their ballheads are not competitive - you can do a lot better. I'm not even sure that their clamping system is of the Arca-Swiss type dovetail design which is what almost everyone uses.
A very popular head with your new tripod is the RRS BH-55, it costs around $450. An equally popular head is the Sirui K-40X, it costs around $170. I was in the B&H store a couple of weeks ago and had the opportunity to use a K-40X and was impressed. It looks to be very good value for money, the one in the store was really beat up but the friction control on it was working fine and although the head looked terrible it worked perfectly. It seems to be a very durable head.
Both of these ballheads are large with 55mm ball diameters and are perfectly suited to your new 3-series.