The Ryobi or the Homelite 25cc are good choices. I have a Homey 25 in mine and the power is OK. The cubs wing is certainly large enough to support the extra weight. I'd recommend moving the firewall back with either engine to assist you with balanceing the plane, And it would be a must with the Ryobi since the engine is very long. BTW neither of these 2 engines will require a CD ignition. Both will hand star nicely with the stock mag ignition system. But I would recommend replacing the stock carb for more fuel flow and replaceing the stock muffler.