WW, I think I found an electric motor for the Argus. You can check me out on this. I estimated a minimum 7hp to move the Argus spryly in a 10 knot wind. Lot of guesswork there I admit.
Power of 11KW [14.75 hp]. Cost is about $850.00 US. A cooling spinner is available with a diameter 115 mm. [4.5") Yes, @50Volts and 220Amps they're running 11KiloWatts of power through this 5" diameter brushless motor! Weight is about 3 lbs. Add 7 lbs of LiPo batteries and you could move the Argus around for two hours with about ten lbs. total propulsion plant. That probably is lighter than the present liquid fueled engine IMO.