Yes, it is probably GH-head, but NONE of us know how large it already was before he started juicing. Also, the huge head does not necessarily mean he is taking hugh amounts of GH. Basically GH will enhance what you genetically already are designed to have. So for Ronnie, it make his lips and head grow, with Jay, it made his chin grow but genetically he already was prone to an elongated chin.
Here's a thought - can someone take a photo of Wong, and then photoshop his head (ie reduce it) to a more normal size (pre-GH) head. That will then detract less from the head, and you will see how good his physique looks with a normal head.