I will once I receive the parts and it's built. However, I've seen people with the exact same build run the game just fine.
I guess I'll just have to see.
I've also seen this build run CPU intensive games like DayZ Mod and the Standalone with around fourty to fifty frames average.
I'll keep you informed once I get it all built!
As for your 2 GTX 770's, are you sure that ArmA is using both of them? Although I'm not active on the forums or use them, I've seen my days with ArmA 2 and it was heavily CPU intensive.
From what I hear, ArmA 3's engine is similar and is also CPU intensive so if you don't have a strong CPU, your 2 GTX 770's won't do anything.