They told you what to do but not how. You need to mount the tank so that the centerline of the tank is even with the throttle barrel of the carb. With a lot of four strokes, that is difficult to do since a lot of planes are designed for two strokes where the carb is above the crank line. Like he said, mount the engine in its side will take care of a lot of the problem. When all else fails, you can use a Perry pump to provide constant fuel pressure. I had to do this on my EZ P-51 racer.