RE: Heli engine for airplane use? Can I?
No reason you couldn't use it. If you can get a prop on it, it'll work.
Now the carb is designed to be a little on the rich side through the mid-range. With heli's they use the mid-range throttle settings most of the time.
So worst case is you might have to change the carb out for a airplane carb, if it is too rich for you in the mid-range throttle settings.
But usually that isnt a problem.