Thunderhead-
My Tanic 830 3S pack weighs about half what your Kokam does. That's a huge difference on a foamy. Other than that, your set up is just like mine. I like the 10x4.7 prop on this. Use the smallest receiver you can. Hitec Electron, Berg 5, Polk Seeker 6, JR 610, etc...
Here’s a couple more pics of upright harriers.
Does it look too heavy?