I did a Balsa USA 1/4 scale and had the Sato 150 inverted, only thing I had to do was cut and weld the exaust manafold to a 90 degree....that way it stuck out the bottom of the cowl..., made a fake right side and left side engine that was hollow and open in the front glued over holes in the cowl for cooling air to go into and a fairly big cutout in the bottom of the cowl....worked like a charm....
Inverted flat spins, short hovers....and a whole lot of other things it wasn't designed to do. (Grinnnnnnn)

BB1
KCRC