RE: Two Speed 280s
The 280BB race motors are similar in performance characteristics to the venerable Speed 300 motor, IIRC. You should be okay treating them as if they were Speed 300s.
There aren't too many direct drive 300 designs on the market. The 300 is too hot of a motor to spin a useful-size prop direct drive in most applications; it would draw too many Amps. One design where it's used quite successfully comes to mind, though: The Graupner Mini Piper from Hobby Lobby.
I don't know if HL still carries the Mini Piper, but IIRC, it used a Gunther Zagi prop on 6 or 7 cells, and weighed about 10 ounces RTF. Either 6 or 7 NiMH cells like KAN1100s, or a 2S ThunderPower 2100 LiPoly would make a good power source.