I have the OS .18 CV-RX in my Evader. It dropped right in and it starts easy with loads of power. No real need to strengthen your drivetrain either. Thats the motor you want.

On top of that, only the Picco engine you linked to has the carb. linkage on the right side. And all of them are slide carbs. You're looking for a rotary carb setup if you want "drop in" easy installation. Slide carbs are more for on raod applications anyway and somewhat of a pain to tune(at least for me).