I do not know, but I suggest that you contact both Gigabyte and "possibly" Zotac support. My suggestion is not a blow-off and here's why:
Your Gigabyte card appears to allow an extra slot worth of space between two SLI'd cards. Pretty awesome if you ask me.
Your Zotac cards are 2.5 slots wide.
I recommend that you use the 2 way SLI bridge that is listed in your motherboard's manual for now, until Gigabyte can direct you to the proper HB bridge. Would you mind sharing your full specs, including your PSU? It's not necessary for your question, but I'm just drooling over your two GPUs and MB.
Gigabyte support: (626) 854-9338