With this engine( which is a great one) I would stick with a monoplane to get lightweight and low wing loading,if you want 3D performance.The Saito will 3D a bipe,but it will have to be a .40-50 size and with all your components added up it will be heavy.Most manouvers will have to be forced with lots of stick input and lots of throttle.3d looks best when the plane and engine can work together well matched.Bi planes need much more power and torque than monoplanes, to do well in aerobatics
Bipes will 3D well,but have to be a considerable size,well built with minimum weight and need an extremely high performance engine.