aeroman, My favorite setup for a gws 300 c-drive is retime the motor for correct rotation, gws-11-8 prop, and 2s2p 1020 kokam lipoly. in my 11.5 oz scratch built it has good vertical accelleration. The setup draws 7 amps static, and your 720 mah pack should come close to the same power, but a little less run time. I get 5-6 minutes wot, or 20-30 minutes just cruising.
If you are not familiar with retiming there are many threads about it
Hope this helps



Dave